diff --git a/src/api.cc b/src/api.cc
index 4e731fb..e11d140 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -1,77 +1,64 @@
 // Copyright 2012 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
 
-#include "api.h"
+#include "src/api.h"
 
-#include <math.h>  // For isnan.
 #include <string.h>  // For memcpy, strlen.
-#include "../include/v8-debug.h"
-#include "../include/v8-profiler.h"
-#include "../include/v8-testing.h"
-#include "bootstrapper.h"
-#include "compiler.h"
-#include "conversions-inl.h"
-#include "counters.h"
-#include "debug.h"
-#include "deoptimizer.h"
-#include "execution.h"
-#include "global-handles.h"
-#include "heap-profiler.h"
-#include "messages.h"
-#ifdef COMPRESS_STARTUP_DATA_BZ2
-#include "natives.h"
-#endif
-#include "parser.h"
-#include "platform.h"
-#include "profile-generator-inl.h"
-#include "property-details.h"
-#include "property.h"
-#include "runtime-profiler.h"
-#include "scanner-character-streams.h"
-#include "snapshot.h"
-#include "unicode-inl.h"
-#include "v8threads.h"
-#include "version.h"
-#include "vm-state-inl.h"
+#ifdef V8_USE_ADDRESS_SANITIZER
+#include <sanitizer/asan_interface.h>
+#endif  // V8_USE_ADDRESS_SANITIZER
+#include <cmath>  // For isnan.
+#include "include/v8-debug.h"
+#include "include/v8-profiler.h"
+#include "include/v8-testing.h"
+#include "src/assert-scope.h"
+#include "src/background-parsing-task.h"
+#include "src/base/platform/platform.h"
+#include "src/base/platform/time.h"
+#include "src/base/utils/random-number-generator.h"
+#include "src/bootstrapper.h"
+#include "src/code-stubs.h"
+#include "src/compiler.h"
+#include "src/conversions-inl.h"
+#include "src/counters.h"
+#include "src/cpu-profiler.h"
+#include "src/debug.h"
+#include "src/deoptimizer.h"
+#include "src/execution.h"
+#include "src/global-handles.h"
+#include "src/heap-profiler.h"
+#include "src/heap-snapshot-generator-inl.h"
+#include "src/icu_util.h"
+#include "src/json-parser.h"
+#include "src/messages.h"
+#include "src/natives.h"
+#include "src/parser.h"
+#include "src/profile-generator-inl.h"
+#include "src/property.h"
+#include "src/property-details.h"
+#include "src/prototype.h"
+#include "src/runtime.h"
+#include "src/runtime-profiler.h"
+#include "src/scanner-character-streams.h"
+#include "src/simulator.h"
+#include "src/snapshot.h"
+#include "src/unicode-inl.h"
+#include "src/v8threads.h"
+#include "src/version.h"
+#include "src/vm-state-inl.h"
 
 
 #define LOG_API(isolate, expr) LOG(isolate, ApiEntryCall(expr))
 
-#define ENTER_V8(isolate)                                        \
-  ASSERT((isolate)->IsInitialized());                           \
-  i::VMState __state__((isolate), i::OTHER)
-#define LEAVE_V8(isolate) \
-  i::VMState __state__((isolate), i::EXTERNAL)
+#define ENTER_V8(isolate)                                          \
+  DCHECK((isolate)->IsInitialized());                              \
+  i::VMState<i::OTHER> __state__((isolate))
 
 namespace v8 {
 
 #define ON_BAILOUT(isolate, location, code)                        \
-  if (IsDeadCheck(isolate, location) ||                            \
-      IsExecutionTerminatingCheck(isolate)) {                      \
+  if (IsExecutionTerminatingCheck(isolate)) {                      \
     code;                                                          \
     UNREACHABLE();                                                 \
   }
@@ -79,7 +66,7 @@
 
 #define EXCEPTION_PREAMBLE(isolate)                                         \
   (isolate)->handle_scope_implementer()->IncrementCallDepth();              \
-  ASSERT(!(isolate)->external_caught_exception());                          \
+  DCHECK(!(isolate)->external_caught_exception());                          \
   bool has_pending_exception = false
 
 
@@ -89,11 +76,6 @@
         (isolate)->handle_scope_implementer();                                 \
     handle_scope_implementer->DecrementCallDepth();                            \
     if (has_pending_exception) {                                               \
-      if (handle_scope_implementer->CallDepthIsZero() &&                       \
-          (isolate)->is_out_of_memory()) {                                     \
-        if (!(isolate)->ignore_out_of_memory())                                \
-          i::V8::FatalProcessOutOfMemory(NULL);                                \
-      }                                                                        \
       bool call_depth_is_zero = handle_scope_implementer->CallDepthIsZero();   \
       (isolate)->OptionalRescheduleException(call_depth_is_zero);              \
       do_callback                                                              \
@@ -105,42 +87,16 @@
 
 #define EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, value)                    \
   EXCEPTION_BAILOUT_CHECK_GENERIC(                                             \
-      isolate, value, i::V8::FireCallCompletedCallback(isolate);)
+      isolate, value, isolate->FireCallCompletedCallback();)
 
 
 #define EXCEPTION_BAILOUT_CHECK(isolate, value)                                \
   EXCEPTION_BAILOUT_CHECK_GENERIC(isolate, value, ;)
 
 
-#define API_ENTRY_CHECK(isolate, msg)                                          \
-  do {                                                                         \
-    if (v8::Locker::IsActive()) {                                              \
-      ApiCheck(isolate->thread_manager()->IsLockedByCurrentThread(),           \
-               msg,                                                            \
-               "Entering the V8 API without proper locking in place");         \
-    }                                                                          \
-  } while (false)
-
-
 // --- E x c e p t i o n   B e h a v i o r ---
 
 
-static void DefaultFatalErrorHandler(const char* location,
-                                     const char* message) {
-  i::VMState __state__(i::Isolate::Current(), i::OTHER);
-  API_Fatal(location, message);
-}
-
-
-static FatalErrorCallback GetFatalErrorHandler() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (isolate->exception_behavior() == NULL) {
-    isolate->set_exception_behavior(DefaultFatalErrorHandler);
-  }
-  return isolate->exception_behavior();
-}
-
-
 void i::FatalProcessOutOfMemory(const char* location) {
   i::V8::FatalProcessOutOfMemory(location, false);
 }
@@ -176,6 +132,10 @@
   heap_stats.cell_space_size = &cell_space_size;
   intptr_t cell_space_capacity;
   heap_stats.cell_space_capacity = &cell_space_capacity;
+  intptr_t property_cell_space_size;
+  heap_stats.property_cell_space_size = &property_cell_space_size;
+  intptr_t property_cell_space_capacity;
+  heap_stats.property_cell_space_capacity = &property_cell_space_capacity;
   intptr_t lo_space_size;
   heap_stats.lo_space_size = &lo_space_size;
   int global_handle_count;
@@ -201,70 +161,34 @@
   int end_marker;
   heap_stats.end_marker = &end_marker;
   i::Isolate* isolate = i::Isolate::Current();
-  // BUG(1718):
-  // Don't use the take_snapshot since we don't support HeapIterator here
-  // without doing a special GC.
-  isolate->heap()->RecordStats(&heap_stats, false);
-  i::V8::SetFatalError();
-  FatalErrorCallback callback = GetFatalErrorHandler();
-  {
-    LEAVE_V8(isolate);
-    callback(location, "Allocation failed - process out of memory");
+  if (isolate->heap()->HasBeenSetUp()) {
+    // BUG(1718): Don't use the take_snapshot since we don't support
+    // HeapIterator here without doing a special GC.
+    isolate->heap()->RecordStats(&heap_stats, false);
   }
-  // If the callback returns, we stop execution.
-  UNREACHABLE();
+  Utils::ApiCheck(false, location, "Allocation failed - process out of memory");
+  // If the fatal error handler returns, we stop execution.
+  FATAL("API fatal error handler returned after process out of memory");
 }
 
 
-bool Utils::ReportApiFailure(const char* location, const char* message) {
-  FatalErrorCallback callback = GetFatalErrorHandler();
-  callback(location, message);
-  i::V8::SetFatalError();
-  return false;
+void Utils::ReportApiFailure(const char* location, const char* message) {
+  i::Isolate* isolate = i::Isolate::Current();
+  FatalErrorCallback callback = isolate->exception_behavior();
+  if (callback == NULL) {
+    base::OS::PrintError("\n#\n# Fatal error in %s\n# %s\n#\n\n", location,
+                         message);
+    base::OS::Abort();
+  } else {
+    callback(location, message);
+  }
+  isolate->SignalFatalError();
 }
 
 
 bool V8::IsDead() {
-  return i::V8::IsDead();
-}
-
-
-static inline bool ApiCheck(bool condition,
-                            const char* location,
-                            const char* message) {
-  return condition ? true : Utils::ReportApiFailure(location, message);
-}
-
-
-static bool ReportV8Dead(const char* location) {
-  FatalErrorCallback callback = GetFatalErrorHandler();
-  callback(location, "V8 is no longer usable");
-  return true;
-}
-
-
-static bool ReportEmptyHandle(const char* location) {
-  FatalErrorCallback callback = GetFatalErrorHandler();
-  callback(location, "Reading from empty handle");
-  return true;
-}
-
-
-/**
- * IsDeadCheck checks that the vm is usable.  If, for instance, the vm has been
- * out of memory at some point this check will fail.  It should be called on
- * entry to all methods that touch anything in the heap, except destructors
- * which you sometimes can't avoid calling after the vm has crashed.  Functions
- * that call EnsureInitialized or ON_BAILOUT don't have to also call
- * IsDeadCheck.  ON_BAILOUT has the advantage over EnsureInitialized that you
- * can arrange to return if the VM is dead.  This is needed to ensure that no VM
- * heap allocations are attempted on a dead VM.  EnsureInitialized has the
- * advantage over ON_BAILOUT that it actually initializes the VM if this has not
- * yet been done.
- */
-static inline bool IsDeadCheck(i::Isolate* isolate, const char* location) {
-  return !isolate->IsInitialized()
-      && i::V8::IsDead() ? ReportV8Dead(location) : false;
+  i::Isolate* isolate = i::Isolate::Current();
+  return isolate->IsDead();
 }
 
 
@@ -278,52 +202,6 @@
 }
 
 
-static inline bool EmptyCheck(const char* location, v8::Handle<v8::Data> obj) {
-  return obj.IsEmpty() ? ReportEmptyHandle(location) : false;
-}
-
-
-static inline bool EmptyCheck(const char* location, const v8::Data* obj) {
-  return (obj == 0) ? ReportEmptyHandle(location) : false;
-}
-
-// --- S t a t i c s ---
-
-
-static bool InitializeHelper() {
-  if (i::Snapshot::Initialize()) return true;
-  return i::V8::Initialize(NULL);
-}
-
-
-static inline bool EnsureInitializedForIsolate(i::Isolate* isolate,
-                                               const char* location) {
-  if (IsDeadCheck(isolate, location)) return false;
-  if (isolate != NULL) {
-    if (isolate->IsInitialized()) return true;
-  }
-  ASSERT(isolate == i::Isolate::Current());
-  return ApiCheck(InitializeHelper(), location, "Error initializing V8");
-}
-
-// Some initializing API functions are called early and may be
-// called on a thread different from static initializer thread.
-// If Isolate API is used, Isolate::Enter() will initialize TLS so
-// Isolate::Current() works. If it's a legacy case, then the thread
-// may not have TLS initialized yet. However, in initializing APIs it
-// may be too early to call EnsureInitialized() - some pre-init
-// parameters still have to be configured.
-static inline i::Isolate* EnterIsolateIfNeeded() {
-  i::Isolate* isolate = i::Isolate::UncheckedCurrent();
-  if (isolate != NULL)
-    return isolate;
-
-  i::Isolate::EnterDefaultIsolate();
-  isolate = i::Isolate::Current();
-  return isolate;
-}
-
-
 StartupDataDecompressor::StartupDataDecompressor()
     : raw_data(i::NewArray<char*>(V8::GetCompressedStartupDataCount())) {
   for (int i = 0; i < V8::GetCompressedStartupDataCount(); ++i) {
@@ -355,7 +233,7 @@
                                   compressed_data[i].compressed_size);
       if (result != 0) return result;
     } else {
-      ASSERT_EQ(0, compressed_data[i].raw_size);
+      DCHECK_EQ(0, compressed_data[i].raw_size);
     }
     compressed_data[i].data = decompressed;
   }
@@ -382,6 +260,7 @@
   kCompressedStartupDataCount
 };
 
+
 int V8::GetCompressedStartupDataCount() {
 #ifdef COMPRESS_STARTUP_DATA_BZ2
   return kCompressedStartupDataCount;
@@ -424,24 +303,24 @@
 
 void V8::SetDecompressedStartupData(StartupData* decompressed_data) {
 #ifdef COMPRESS_STARTUP_DATA_BZ2
-  ASSERT_EQ(i::Snapshot::raw_size(), decompressed_data[kSnapshot].raw_size);
+  DCHECK_EQ(i::Snapshot::raw_size(), decompressed_data[kSnapshot].raw_size);
   i::Snapshot::set_raw_data(
       reinterpret_cast<const i::byte*>(decompressed_data[kSnapshot].data));
 
-  ASSERT_EQ(i::Snapshot::context_raw_size(),
+  DCHECK_EQ(i::Snapshot::context_raw_size(),
             decompressed_data[kSnapshotContext].raw_size);
   i::Snapshot::set_context_raw_data(
       reinterpret_cast<const i::byte*>(
           decompressed_data[kSnapshotContext].data));
 
-  ASSERT_EQ(i::Natives::GetRawScriptsSize(),
+  DCHECK_EQ(i::Natives::GetRawScriptsSize(),
             decompressed_data[kLibraries].raw_size);
   i::Vector<const char> libraries_source(
       decompressed_data[kLibraries].data,
       decompressed_data[kLibraries].raw_size);
   i::Natives::SetRawScriptsSource(libraries_source);
 
-  ASSERT_EQ(i::ExperimentalNatives::GetRawScriptsSize(),
+  DCHECK_EQ(i::ExperimentalNatives::GetRawScriptsSize(),
             decompressed_data[kExperimentalLibraries].raw_size);
   i::Vector<const char> exp_libraries_source(
       decompressed_data[kExperimentalLibraries].data,
@@ -451,27 +330,37 @@
 }
 
 
+void V8::SetNativesDataBlob(StartupData* natives_blob) {
+#ifdef V8_USE_EXTERNAL_STARTUP_DATA
+  i::SetNativesFromFile(natives_blob);
+#else
+  CHECK(false);
+#endif
+}
+
+
+void V8::SetSnapshotDataBlob(StartupData* snapshot_blob) {
+#ifdef V8_USE_EXTERNAL_STARTUP_DATA
+  i::SetSnapshotFromFile(snapshot_blob);
+#else
+  CHECK(false);
+#endif
+}
+
+
 void V8::SetFatalErrorHandler(FatalErrorCallback that) {
-  i::Isolate* isolate = EnterIsolateIfNeeded();
+  i::Isolate* isolate = i::Isolate::Current();
   isolate->set_exception_behavior(that);
 }
 
 
 void V8::SetAllowCodeGenerationFromStringsCallback(
     AllowCodeGenerationFromStringsCallback callback) {
-  i::Isolate* isolate = EnterIsolateIfNeeded();
+  i::Isolate* isolate = i::Isolate::Current();
   isolate->set_allow_code_gen_callback(callback);
 }
 
 
-#ifdef DEBUG
-void ImplementationUtilities::ZapHandleRange(i::Object** begin,
-                                             i::Object** end) {
-  i::HandleScope::ZapRange(begin, end);
-}
-#endif
-
-
 void V8::SetFlagsFromString(const char* str, int length) {
   i::FlagList::SetFlagsFromString(str, length);
 }
@@ -482,23 +371,6 @@
 }
 
 
-v8::Handle<Value> ThrowException(v8::Handle<v8::Value> value) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::ThrowException()")) {
-    return v8::Handle<Value>();
-  }
-  ENTER_V8(isolate);
-  // If we're passed an empty handle, we throw an undefined exception
-  // to deal more gracefully with out of memory situations.
-  if (value.IsEmpty()) {
-    isolate->ScheduleThrow(isolate->heap()->undefined_value());
-  } else {
-    isolate->ScheduleThrow(*Utils::OpenHandle(*value));
-  }
-  return v8::Undefined();
-}
-
-
 RegisteredExtension* RegisteredExtension::first_extension_ = NULL;
 
 
@@ -512,6 +384,17 @@
 }
 
 
+void RegisteredExtension::UnregisterAll() {
+  RegisteredExtension* re = first_extension_;
+  while (re != NULL) {
+    RegisteredExtension* next = re->next();
+    delete re;
+    re = next;
+  }
+  first_extension_ = NULL;
+}
+
+
 void RegisterExtension(Extension* that) {
   RegisteredExtension* extension = new RegisteredExtension(that);
   RegisteredExtension::Register(extension);
@@ -530,281 +413,297 @@
       source_(source, source_length_),
       dep_count_(dep_count),
       deps_(deps),
-      auto_enable_(false) { }
-
-
-v8::Handle<Primitive> Undefined() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!EnsureInitializedForIsolate(isolate, "v8::Undefined()")) {
-    return v8::Handle<v8::Primitive>();
-  }
-  return v8::Handle<Primitive>(ToApi<Primitive>(
-      isolate->factory()->undefined_value()));
-}
-
-
-v8::Handle<Primitive> Null() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!EnsureInitializedForIsolate(isolate, "v8::Null()")) {
-    return v8::Handle<v8::Primitive>();
-  }
-  return v8::Handle<Primitive>(
-      ToApi<Primitive>(isolate->factory()->null_value()));
-}
-
-
-v8::Handle<Boolean> True() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!EnsureInitializedForIsolate(isolate, "v8::True()")) {
-    return v8::Handle<Boolean>();
-  }
-  return v8::Handle<Boolean>(
-      ToApi<Boolean>(isolate->factory()->true_value()));
-}
-
-
-v8::Handle<Boolean> False() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!EnsureInitializedForIsolate(isolate, "v8::False()")) {
-    return v8::Handle<Boolean>();
-  }
-  return v8::Handle<Boolean>(
-      ToApi<Boolean>(isolate->factory()->false_value()));
+      auto_enable_(false) {
+  CHECK(source != NULL || source_length_ == 0);
 }
 
 
 ResourceConstraints::ResourceConstraints()
-  : max_young_space_size_(0),
-    max_old_space_size_(0),
-    max_executable_size_(0),
-    stack_limit_(NULL) { }
+    : max_semi_space_size_(0),
+      max_old_space_size_(0),
+      max_executable_size_(0),
+      stack_limit_(NULL),
+      max_available_threads_(0),
+      code_range_size_(0) { }
 
+void ResourceConstraints::ConfigureDefaults(uint64_t physical_memory,
+                                            uint64_t virtual_memory_limit,
+                                            uint32_t number_of_processors) {
+#if V8_OS_ANDROID
+  // Android has higher physical memory requirements before raising the maximum
+  // heap size limits since it has no swap space.
+  const uint64_t low_limit = 512ul * i::MB;
+  const uint64_t medium_limit = 1ul * i::GB;
+  const uint64_t high_limit = 2ul * i::GB;
+#else
+  const uint64_t low_limit = 512ul * i::MB;
+  const uint64_t medium_limit = 768ul * i::MB;
+  const uint64_t high_limit = 1ul  * i::GB;
+#endif
 
-bool SetResourceConstraints(ResourceConstraints* constraints) {
-  i::Isolate* isolate = EnterIsolateIfNeeded();
-
-  int young_space_size = constraints->max_young_space_size();
-  int old_gen_size = constraints->max_old_space_size();
-  int max_executable_size = constraints->max_executable_size();
-  if (young_space_size != 0 || old_gen_size != 0 || max_executable_size != 0) {
-    // After initialization it's too late to change Heap constraints.
-    ASSERT(!isolate->IsInitialized());
-    bool result = isolate->heap()->ConfigureHeap(young_space_size / 2,
-                                                 old_gen_size,
-                                                 max_executable_size);
-    if (!result) return false;
+  if (physical_memory <= low_limit) {
+    set_max_semi_space_size(i::Heap::kMaxSemiSpaceSizeLowMemoryDevice);
+    set_max_old_space_size(i::Heap::kMaxOldSpaceSizeLowMemoryDevice);
+    set_max_executable_size(i::Heap::kMaxExecutableSizeLowMemoryDevice);
+  } else if (physical_memory <= medium_limit) {
+    set_max_semi_space_size(i::Heap::kMaxSemiSpaceSizeMediumMemoryDevice);
+    set_max_old_space_size(i::Heap::kMaxOldSpaceSizeMediumMemoryDevice);
+    set_max_executable_size(i::Heap::kMaxExecutableSizeMediumMemoryDevice);
+  } else if (physical_memory <= high_limit) {
+    set_max_semi_space_size(i::Heap::kMaxSemiSpaceSizeHighMemoryDevice);
+    set_max_old_space_size(i::Heap::kMaxOldSpaceSizeHighMemoryDevice);
+    set_max_executable_size(i::Heap::kMaxExecutableSizeHighMemoryDevice);
+  } else {
+    set_max_semi_space_size(i::Heap::kMaxSemiSpaceSizeHugeMemoryDevice);
+    set_max_old_space_size(i::Heap::kMaxOldSpaceSizeHugeMemoryDevice);
+    set_max_executable_size(i::Heap::kMaxExecutableSizeHugeMemoryDevice);
   }
-  if (constraints->stack_limit() != NULL) {
-    uintptr_t limit = reinterpret_cast<uintptr_t>(constraints->stack_limit());
-    isolate->stack_guard()->SetStackLimit(limit);
+
+  set_max_available_threads(i::Max(i::Min(number_of_processors, 4u), 1u));
+
+  if (virtual_memory_limit > 0 && i::kRequiresCodeRange) {
+    // Reserve no more than 1/8 of the memory for the code range, but at most
+    // kMaximalCodeRangeSize.
+    set_code_range_size(
+        i::Min(i::kMaximalCodeRangeSize / i::MB,
+               static_cast<size_t>((virtual_memory_limit >> 3) / i::MB)));
   }
-  return true;
 }
 
 
-i::Object** V8::GlobalizeReference(i::Object** obj) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "V8::Persistent::New")) return NULL;
+void SetResourceConstraints(i::Isolate* isolate,
+                            const ResourceConstraints& constraints) {
+  int semi_space_size = constraints.max_semi_space_size();
+  int old_space_size = constraints.max_old_space_size();
+  int max_executable_size = constraints.max_executable_size();
+  size_t code_range_size = constraints.code_range_size();
+  if (semi_space_size != 0 || old_space_size != 0 ||
+      max_executable_size != 0 || code_range_size != 0) {
+    isolate->heap()->ConfigureHeap(semi_space_size, old_space_size,
+                                   max_executable_size, code_range_size);
+  }
+  if (constraints.stack_limit() != NULL) {
+    uintptr_t limit = reinterpret_cast<uintptr_t>(constraints.stack_limit());
+    isolate->stack_guard()->SetStackLimit(limit);
+  }
+
+  isolate->set_max_available_threads(constraints.max_available_threads());
+}
+
+
+i::Object** V8::GlobalizeReference(i::Isolate* isolate, i::Object** obj) {
   LOG_API(isolate, "Persistent::New");
-  i::Handle<i::Object> result =
-      isolate->global_handles()->Create(*obj);
+  i::Handle<i::Object> result = isolate->global_handles()->Create(*obj);
+#ifdef DEBUG
+  (*obj)->ObjectVerify();
+#endif  // DEBUG
   return result.location();
 }
 
 
-void V8::MakeWeak(i::Object** object, void* parameters,
-                  WeakReferenceCallback callback) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "MakeWeak");
-  isolate->global_handles()->MakeWeak(object, parameters,
-                                                    callback);
+i::Object** V8::CopyPersistent(i::Object** obj) {
+  i::Handle<i::Object> result = i::GlobalHandles::CopyGlobal(obj);
+#ifdef DEBUG
+  (*obj)->ObjectVerify();
+#endif  // DEBUG
+  return result.location();
 }
 
 
-void V8::ClearWeak(i::Object** obj) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "ClearWeak");
-  isolate->global_handles()->ClearWeakness(obj);
+void V8::MakeWeak(i::Object** object,
+                  void* parameters,
+                  WeakCallback weak_callback) {
+  i::GlobalHandles::MakeWeak(object, parameters, weak_callback);
 }
 
 
-void V8::MarkIndependent(i::Object** object) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "MakeIndependent");
-  isolate->global_handles()->MarkIndependent(object);
-}
-
-
-bool V8::IsGlobalNearDeath(i::Object** obj) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "IsGlobalNearDeath");
-  if (!isolate->IsInitialized()) return false;
-  return i::GlobalHandles::IsNearDeath(obj);
-}
-
-
-bool V8::IsGlobalWeak(i::Object** obj) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "IsGlobalWeak");
-  if (!isolate->IsInitialized()) return false;
-  return i::GlobalHandles::IsWeak(obj);
+void* V8::ClearWeak(i::Object** obj) {
+  return i::GlobalHandles::ClearWeakness(obj);
 }
 
 
 void V8::DisposeGlobal(i::Object** obj) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "DisposeGlobal");
-  if (!isolate->IsInitialized()) return;
-  isolate->global_handles()->Destroy(obj);
+  i::GlobalHandles::Destroy(obj);
 }
 
+
+void V8::Eternalize(Isolate* v8_isolate, Value* value, int* index) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  i::Object* object = *Utils::OpenHandle(value);
+  isolate->eternal_handles()->Create(isolate, object, index);
+}
+
+
+Local<Value> V8::GetEternal(Isolate* v8_isolate, int index) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  return Utils::ToLocal(isolate->eternal_handles()->Get(index));
+}
+
+
 // --- H a n d l e s ---
 
 
-HandleScope::HandleScope() {
-  i::Isolate* isolate = i::Isolate::Current();
-  API_ENTRY_CHECK(isolate, "HandleScope::HandleScope");
-  v8::ImplementationUtilities::HandleScopeData* current =
-      isolate->handle_scope_data();
-  isolate_ = isolate;
+HandleScope::HandleScope(Isolate* isolate) {
+  Initialize(isolate);
+}
+
+
+void HandleScope::Initialize(Isolate* isolate) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  // We do not want to check the correct usage of the Locker class all over the
+  // place, so we do it only here: Without a HandleScope, an embedder can do
+  // almost nothing, so it is enough to check in this central place.
+  Utils::ApiCheck(!v8::Locker::IsActive() ||
+                  internal_isolate->thread_manager()->IsLockedByCurrentThread(),
+                  "HandleScope::HandleScope",
+                  "Entering the V8 API without proper locking in place");
+  i::HandleScopeData* current = internal_isolate->handle_scope_data();
+  isolate_ = internal_isolate;
   prev_next_ = current->next;
   prev_limit_ = current->limit;
-  is_closed_ = false;
   current->level++;
 }
 
 
 HandleScope::~HandleScope() {
-  if (!is_closed_) {
-    Leave();
+  i::HandleScope::CloseScope(isolate_, prev_next_, prev_limit_);
+}
+
+
+int HandleScope::NumberOfHandles(Isolate* isolate) {
+  return i::HandleScope::NumberOfHandles(
+      reinterpret_cast<i::Isolate*>(isolate));
+}
+
+
+i::Object** HandleScope::CreateHandle(i::Isolate* isolate, i::Object* value) {
+  return i::HandleScope::CreateHandle(isolate, value);
+}
+
+
+i::Object** HandleScope::CreateHandle(i::HeapObject* heap_object,
+                                      i::Object* value) {
+  DCHECK(heap_object->IsHeapObject());
+  return i::HandleScope::CreateHandle(heap_object->GetIsolate(), value);
+}
+
+
+EscapableHandleScope::EscapableHandleScope(Isolate* v8_isolate) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  escape_slot_ = CreateHandle(isolate, isolate->heap()->the_hole_value());
+  Initialize(v8_isolate);
+}
+
+
+i::Object** EscapableHandleScope::Escape(i::Object** escape_value) {
+  i::Heap* heap = reinterpret_cast<i::Isolate*>(GetIsolate())->heap();
+  Utils::ApiCheck(*escape_slot_ == heap->the_hole_value(),
+                  "EscapeableHandleScope::Escape",
+                  "Escape value set twice");
+  if (escape_value == NULL) {
+    *escape_slot_ = heap->undefined_value();
+    return NULL;
   }
-}
-
-
-void HandleScope::Leave() {
-  ASSERT(isolate_ == i::Isolate::Current());
-  v8::ImplementationUtilities::HandleScopeData* current =
-      isolate_->handle_scope_data();
-  current->level--;
-  ASSERT(current->level >= 0);
-  current->next = prev_next_;
-  if (current->limit != prev_limit_) {
-    current->limit = prev_limit_;
-    i::HandleScope::DeleteExtensions(isolate_);
-  }
-
-#ifdef DEBUG
-  i::HandleScope::ZapRange(prev_next_, prev_limit_);
-#endif
-}
-
-
-int HandleScope::NumberOfHandles() {
-  EnsureInitializedForIsolate(
-      i::Isolate::Current(), "HandleScope::NumberOfHandles");
-  return i::HandleScope::NumberOfHandles();
-}
-
-
-i::Object** HandleScope::CreateHandle(i::Object* value) {
-  return i::HandleScope::CreateHandle(value, i::Isolate::Current());
-}
-
-
-i::Object** HandleScope::CreateHandle(i::HeapObject* value) {
-  ASSERT(value->IsHeapObject());
-  return reinterpret_cast<i::Object**>(
-      i::HandleScope::CreateHandle(value, value->GetIsolate()));
+  *escape_slot_ = *escape_value;
+  return escape_slot_;
 }
 
 
 void Context::Enter() {
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Isolate* isolate = env->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Context::Enter()")) return;
   ENTER_V8(isolate);
-
-  isolate->handle_scope_implementer()->EnterContext(env);
-
-  isolate->handle_scope_implementer()->SaveContext(isolate->context());
+  i::HandleScopeImplementer* impl = isolate->handle_scope_implementer();
+  impl->EnterContext(env);
+  impl->SaveContext(isolate->context());
   isolate->set_context(*env);
 }
 
 
 void Context::Exit() {
-  // Exit is essentially a static function and doesn't use the
-  // receiver, so we have to get the current isolate from the thread
-  // local.
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!isolate->IsInitialized()) return;
-
-  if (!ApiCheck(isolate->handle_scope_implementer()->LeaveLastContext(),
-                "v8::Context::Exit()",
-                "Cannot exit non-entered context")) {
+  i::Handle<i::Context> env = Utils::OpenHandle(this);
+  i::Isolate* isolate = env->GetIsolate();
+  ENTER_V8(isolate);
+  i::HandleScopeImplementer* impl = isolate->handle_scope_implementer();
+  if (!Utils::ApiCheck(impl->LastEnteredContextWas(env),
+                       "v8::Context::Exit()",
+                       "Cannot exit non-entered context")) {
     return;
   }
-
-  // Content of 'last_context' could be NULL.
-  i::Context* last_context =
-      isolate->handle_scope_implementer()->RestoreContext();
-  isolate->set_context(last_context);
-  isolate->set_context_exit_happened(true);
+  impl->LeaveContext();
+  isolate->set_context(impl->RestoreContext());
 }
 
 
-void Context::SetData(v8::Handle<String> data) {
-  i::Handle<i::Context> env = Utils::OpenHandle(this);
-  i::Isolate* isolate = env->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Context::SetData()")) return;
-  i::Handle<i::Object> raw_data = Utils::OpenHandle(*data);
-  ASSERT(env->IsGlobalContext());
-  if (env->IsGlobalContext()) {
-    env->set_data(*raw_data);
-  }
+static void* DecodeSmiToAligned(i::Object* value, const char* location) {
+  Utils::ApiCheck(value->IsSmi(), location, "Not a Smi");
+  return reinterpret_cast<void*>(value);
 }
 
 
-v8::Local<v8::Value> Context::GetData() {
-  i::Handle<i::Context> env = Utils::OpenHandle(this);
-  i::Isolate* isolate = env->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Context::GetData()")) {
-    return v8::Local<Value>();
+static i::Smi* EncodeAlignedAsSmi(void* value, const char* location) {
+  i::Smi* smi = reinterpret_cast<i::Smi*>(value);
+  Utils::ApiCheck(smi->IsSmi(), location, "Pointer is not aligned");
+  return smi;
+}
+
+
+static i::Handle<i::FixedArray> EmbedderDataFor(Context* context,
+                                                int index,
+                                                bool can_grow,
+                                                const char* location) {
+  i::Handle<i::Context> env = Utils::OpenHandle(context);
+  bool ok =
+      Utils::ApiCheck(env->IsNativeContext(),
+                      location,
+                      "Not a native context") &&
+      Utils::ApiCheck(index >= 0, location, "Negative index");
+  if (!ok) return i::Handle<i::FixedArray>();
+  i::Handle<i::FixedArray> data(env->embedder_data());
+  if (index < data->length()) return data;
+  if (!Utils::ApiCheck(can_grow, location, "Index too large")) {
+    return i::Handle<i::FixedArray>();
   }
-  i::Object* raw_result = NULL;
-  ASSERT(env->IsGlobalContext());
-  if (env->IsGlobalContext()) {
-    raw_result = env->data();
-  } else {
-    return Local<Value>();
-  }
-  i::Handle<i::Object> result(raw_result, isolate);
+  int new_size = i::Max(index, data->length() << 1) + 1;
+  data = i::FixedArray::CopySize(data, new_size);
+  env->set_embedder_data(*data);
+  return data;
+}
+
+
+v8::Local<v8::Value> Context::SlowGetEmbedderData(int index) {
+  const char* location = "v8::Context::GetEmbedderData()";
+  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, false, location);
+  if (data.is_null()) return Local<Value>();
+  i::Handle<i::Object> result(data->get(index), data->GetIsolate());
   return Utils::ToLocal(result);
 }
 
 
-i::Object** v8::HandleScope::RawClose(i::Object** value) {
-  if (!ApiCheck(!is_closed_,
-                "v8::HandleScope::Close()",
-                "Local scope has already been closed")) {
-    return 0;
-  }
-  LOG_API(isolate_, "CloseHandleScope");
+void Context::SetEmbedderData(int index, v8::Handle<Value> value) {
+  const char* location = "v8::Context::SetEmbedderData()";
+  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, true, location);
+  if (data.is_null()) return;
+  i::Handle<i::Object> val = Utils::OpenHandle(*value);
+  data->set(index, *val);
+  DCHECK_EQ(*Utils::OpenHandle(*value),
+            *Utils::OpenHandle(*GetEmbedderData(index)));
+}
 
-  // Read the result before popping the handle block.
-  i::Object* result = NULL;
-  if (value != NULL) {
-    result = *value;
-  }
-  is_closed_ = true;
-  Leave();
 
-  if (value == NULL) {
-    return NULL;
-  }
+void* Context::SlowGetAlignedPointerFromEmbedderData(int index) {
+  const char* location = "v8::Context::GetAlignedPointerFromEmbedderData()";
+  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, false, location);
+  if (data.is_null()) return NULL;
+  return DecodeSmiToAligned(data->get(index), location);
+}
 
-  // Allocate a new handle on the previous handle block.
-  i::Handle<i::Object> handle(result);
-  return handle.location();
+
+void Context::SetAlignedPointerInEmbedderData(int index, void* value) {
+  const char* location = "v8::Context::SetAlignedPointerInEmbedderData()";
+  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, true, location);
+  data->set(index, EncodeAlignedAsSmi(value, location));
+  DCHECK_EQ(value, GetAlignedPointerFromEmbedderData(index));
 }
 
 
@@ -816,9 +715,7 @@
 // objects.  To remind you about this there is no HandleScope in the
 // NeanderObject constructor.  When you add one to the site calling the
 // constructor you should check that you ensured the VM was not dead first.
-NeanderObject::NeanderObject(int size) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Nowhere");
+NeanderObject::NeanderObject(v8::internal::Isolate* isolate, int size) {
   ENTER_V8(isolate);
   value_ = isolate->factory()->NewNeanderObject();
   i::Handle<i::FixedArray> elements = isolate->factory()->NewFixedArray(size);
@@ -831,7 +728,7 @@
 }
 
 
-NeanderArray::NeanderArray() : obj_(2) {
+NeanderArray::NeanderArray(v8::internal::Isolate* isolate) : obj_(isolate, 2) {
   obj_.set(0, i::Smi::FromInt(0));
 }
 
@@ -842,8 +739,8 @@
 
 
 i::Object* NeanderArray::get(int offset) {
-  ASSERT(0 <= offset);
-  ASSERT(offset < length());
+  DCHECK(0 <= offset);
+  DCHECK(offset < length());
   return obj_.get(offset + 1);
 }
 
@@ -857,7 +754,8 @@
   int length = this->length();
   int size = obj_.size();
   if (length == size - 1) {
-    i::Handle<i::FixedArray> new_elms = FACTORY->NewFixedArray(2 * size);
+    i::Factory* factory = i::Isolate::Current()->factory();
+    i::Handle<i::FixedArray> new_elms = factory->NewFixedArray(2 * size);
     for (int i = 0; i < length; i++)
       new_elms->set(i + 1, get(i));
     obj_.value()->set_elements(*new_elms);
@@ -881,95 +779,155 @@
 }
 
 
-void Template::Set(v8::Handle<String> name, v8::Handle<Data> value,
-                   v8::PropertyAttribute attribute) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Template::Set()")) return;
-  ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  i::Handle<i::Object> list(Utils::OpenHandle(this)->property_list());
+static void TemplateSet(i::Isolate* isolate,
+                        v8::Template* templ,
+                        int length,
+                        v8::Handle<v8::Data>* data) {
+  i::Handle<i::Object> list(Utils::OpenHandle(templ)->property_list(), isolate);
   if (list->IsUndefined()) {
-    list = NeanderArray().value();
-    Utils::OpenHandle(this)->set_property_list(*list);
+    list = NeanderArray(isolate).value();
+    Utils::OpenHandle(templ)->set_property_list(*list);
   }
   NeanderArray array(list);
-  array.add(Utils::OpenHandle(*name));
-  array.add(Utils::OpenHandle(*value));
-  array.add(Utils::OpenHandle(*v8::Integer::New(attribute)));
+  array.add(isolate->factory()->NewNumberFromInt(length));
+  for (int i = 0; i < length; i++) {
+    i::Handle<i::Object> value = data[i].IsEmpty() ?
+        i::Handle<i::Object>(isolate->factory()->undefined_value()) :
+        Utils::OpenHandle(*data[i]);
+    array.add(value);
+  }
+}
+
+
+void Template::Set(v8::Handle<Name> name,
+                   v8::Handle<Data> value,
+                   v8::PropertyAttribute attribute) {
+  i::Isolate* isolate = i::Isolate::Current();
+  ENTER_V8(isolate);
+  i::HandleScope scope(isolate);
+  const int kSize = 3;
+  v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate);
+  v8::Handle<v8::Data> data[kSize] = {
+    name,
+    value,
+    v8::Integer::New(v8_isolate, attribute)};
+  TemplateSet(isolate, this, kSize, data);
+}
+
+
+void Template::SetAccessorProperty(
+    v8::Local<v8::Name> name,
+    v8::Local<FunctionTemplate> getter,
+    v8::Local<FunctionTemplate> setter,
+    v8::PropertyAttribute attribute,
+    v8::AccessControl access_control) {
+  // TODO(verwaest): Remove |access_control|.
+  DCHECK_EQ(v8::DEFAULT, access_control);
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ENTER_V8(isolate);
+  DCHECK(!name.IsEmpty());
+  DCHECK(!getter.IsEmpty() || !setter.IsEmpty());
+  i::HandleScope scope(isolate);
+  const int kSize = 5;
+  v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate);
+  v8::Handle<v8::Data> data[kSize] = {
+    name,
+    getter,
+    setter,
+    v8::Integer::New(v8_isolate, attribute)};
+  TemplateSet(isolate, this, kSize, data);
 }
 
 
 // --- F u n c t i o n   T e m p l a t e ---
 static void InitializeFunctionTemplate(
-      i::Handle<i::FunctionTemplateInfo> info) {
+    i::Handle<i::FunctionTemplateInfo> info) {
   info->set_tag(i::Smi::FromInt(Consts::FUNCTION_TEMPLATE));
   info->set_flag(0);
 }
 
 
 Local<ObjectTemplate> FunctionTemplate::PrototypeTemplate() {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::PrototypeTemplate()")) {
-    return Local<ObjectTemplate>();
-  }
-  ENTER_V8(isolate);
-  i::Handle<i::Object> result(Utils::OpenHandle(this)->prototype_template());
+  i::Isolate* i_isolate = Utils::OpenHandle(this)->GetIsolate();
+  ENTER_V8(i_isolate);
+  i::Handle<i::Object> result(Utils::OpenHandle(this)->prototype_template(),
+                              i_isolate);
   if (result->IsUndefined()) {
-    result = Utils::OpenHandle(*ObjectTemplate::New());
+    v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(i_isolate);
+    result = Utils::OpenHandle(*ObjectTemplate::New(isolate));
     Utils::OpenHandle(this)->set_prototype_template(*result);
   }
-  return Local<ObjectTemplate>(ToApi<ObjectTemplate>(result));
+  return ToApiHandle<ObjectTemplate>(result);
 }
 
 
 void FunctionTemplate::Inherit(v8::Handle<FunctionTemplate> value) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::Inherit()")) return;
   ENTER_V8(isolate);
   Utils::OpenHandle(this)->set_parent_template(*Utils::OpenHandle(*value));
 }
 
 
-Local<FunctionTemplate> FunctionTemplate::New(InvocationCallback callback,
-    v8::Handle<Value> data, v8::Handle<Signature> signature) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::FunctionTemplate::New()");
-  LOG_API(isolate, "FunctionTemplate::New");
-  ENTER_V8(isolate);
+static Local<FunctionTemplate> FunctionTemplateNew(
+    i::Isolate* isolate,
+    FunctionCallback callback,
+    v8::Handle<Value> data,
+    v8::Handle<Signature> signature,
+    int length,
+    bool do_not_cache) {
   i::Handle<i::Struct> struct_obj =
       isolate->factory()->NewStruct(i::FUNCTION_TEMPLATE_INFO_TYPE);
   i::Handle<i::FunctionTemplateInfo> obj =
       i::Handle<i::FunctionTemplateInfo>::cast(struct_obj);
   InitializeFunctionTemplate(obj);
-  int next_serial_number = isolate->next_serial_number();
-  isolate->set_next_serial_number(next_serial_number + 1);
+  obj->set_do_not_cache(do_not_cache);
+  int next_serial_number = 0;
+  if (!do_not_cache) {
+    next_serial_number = isolate->next_serial_number() + 1;
+    isolate->set_next_serial_number(next_serial_number);
+  }
   obj->set_serial_number(i::Smi::FromInt(next_serial_number));
   if (callback != 0) {
-    if (data.IsEmpty()) data = v8::Undefined();
+    if (data.IsEmpty()) {
+      data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+    }
     Utils::ToLocal(obj)->SetCallHandler(callback, data);
   }
+  obj->set_length(length);
   obj->set_undetectable(false);
   obj->set_needs_access_check(false);
-
   if (!signature.IsEmpty())
     obj->set_signature(*Utils::OpenHandle(*signature));
   return Utils::ToLocal(obj);
 }
 
+Local<FunctionTemplate> FunctionTemplate::New(
+    Isolate* isolate,
+    FunctionCallback callback,
+    v8::Handle<Value> data,
+    v8::Handle<Signature> signature,
+    int length) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "FunctionTemplate::New");
+  ENTER_V8(i_isolate);
+  return FunctionTemplateNew(
+      i_isolate, callback, data, signature, length, false);
+}
 
-Local<Signature> Signature::New(Handle<FunctionTemplate> receiver,
-      int argc, Handle<FunctionTemplate> argv[]) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Signature::New()");
-  LOG_API(isolate, "Signature::New");
-  ENTER_V8(isolate);
+
+Local<Signature> Signature::New(Isolate* isolate,
+                                Handle<FunctionTemplate> receiver, int argc,
+                                Handle<FunctionTemplate> argv[]) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "Signature::New");
+  ENTER_V8(i_isolate);
   i::Handle<i::Struct> struct_obj =
-      isolate->factory()->NewStruct(i::SIGNATURE_INFO_TYPE);
+      i_isolate->factory()->NewStruct(i::SIGNATURE_INFO_TYPE);
   i::Handle<i::SignatureInfo> obj =
       i::Handle<i::SignatureInfo>::cast(struct_obj);
   if (!receiver.IsEmpty()) obj->set_receiver(*Utils::OpenHandle(*receiver));
   if (argc > 0) {
-    i::Handle<i::FixedArray> args = isolate->factory()->NewFixedArray(argc);
+    i::Handle<i::FixedArray> args = i_isolate->factory()->NewFixedArray(argc);
     for (int i = 0; i < argc; i++) {
       if (!argv[i].IsEmpty())
         args->set(i, *Utils::OpenHandle(*argv[i]));
@@ -980,6 +938,129 @@
 }
 
 
+Local<AccessorSignature> AccessorSignature::New(
+    Isolate* isolate,
+    Handle<FunctionTemplate> receiver) {
+  return Utils::AccessorSignatureToLocal(Utils::OpenHandle(*receiver));
+}
+
+
+template<typename Operation>
+static Local<Operation> NewDescriptor(
+    Isolate* isolate,
+    const i::DeclaredAccessorDescriptorData& data,
+    Data* previous_descriptor) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::Handle<i::DeclaredAccessorDescriptor> previous =
+      i::Handle<i::DeclaredAccessorDescriptor>();
+  if (previous_descriptor != NULL) {
+    previous = Utils::OpenHandle(
+        static_cast<DeclaredAccessorDescriptor*>(previous_descriptor));
+  }
+  i::Handle<i::DeclaredAccessorDescriptor> descriptor =
+      i::DeclaredAccessorDescriptor::Create(internal_isolate, data, previous);
+  return Utils::Convert<i::DeclaredAccessorDescriptor, Operation>(descriptor);
+}
+
+
+Local<RawOperationDescriptor>
+ObjectOperationDescriptor::NewInternalFieldDereference(
+    Isolate* isolate,
+    int internal_field) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorObjectDereference;
+  data.object_dereference_descriptor.internal_field = internal_field;
+  return NewDescriptor<RawOperationDescriptor>(isolate, data, NULL);
+}
+
+
+Local<RawOperationDescriptor> RawOperationDescriptor::NewRawShift(
+    Isolate* isolate,
+    int16_t byte_offset) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorPointerShift;
+  data.pointer_shift_descriptor.byte_offset = byte_offset;
+  return NewDescriptor<RawOperationDescriptor>(isolate, data, this);
+}
+
+
+Local<DeclaredAccessorDescriptor> RawOperationDescriptor::NewHandleDereference(
+    Isolate* isolate) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorReturnObject;
+  return NewDescriptor<DeclaredAccessorDescriptor>(isolate, data, this);
+}
+
+
+Local<RawOperationDescriptor> RawOperationDescriptor::NewRawDereference(
+    Isolate* isolate) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorPointerDereference;
+  return NewDescriptor<RawOperationDescriptor>(isolate, data, this);
+}
+
+
+Local<DeclaredAccessorDescriptor> RawOperationDescriptor::NewPointerCompare(
+    Isolate* isolate,
+    void* compare_value) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorPointerCompare;
+  data.pointer_compare_descriptor.compare_value = compare_value;
+  return NewDescriptor<DeclaredAccessorDescriptor>(isolate, data, this);
+}
+
+
+Local<DeclaredAccessorDescriptor> RawOperationDescriptor::NewPrimitiveValue(
+    Isolate* isolate,
+    DeclaredAccessorDescriptorDataType data_type,
+    uint8_t bool_offset) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorPrimitiveValue;
+  data.primitive_value_descriptor.data_type = data_type;
+  data.primitive_value_descriptor.bool_offset = bool_offset;
+  return NewDescriptor<DeclaredAccessorDescriptor>(isolate, data, this);
+}
+
+
+template<typename T>
+static Local<DeclaredAccessorDescriptor> NewBitmaskCompare(
+    Isolate* isolate,
+    T bitmask,
+    T compare_value,
+    RawOperationDescriptor* operation) {
+  i::DeclaredAccessorDescriptorData data;
+  data.type = i::kDescriptorBitmaskCompare;
+  data.bitmask_compare_descriptor.bitmask = bitmask;
+  data.bitmask_compare_descriptor.compare_value = compare_value;
+  data.bitmask_compare_descriptor.size = sizeof(T);
+  return NewDescriptor<DeclaredAccessorDescriptor>(isolate, data, operation);
+}
+
+
+Local<DeclaredAccessorDescriptor> RawOperationDescriptor::NewBitmaskCompare8(
+    Isolate* isolate,
+    uint8_t bitmask,
+    uint8_t compare_value) {
+  return NewBitmaskCompare(isolate, bitmask, compare_value, this);
+}
+
+
+Local<DeclaredAccessorDescriptor> RawOperationDescriptor::NewBitmaskCompare16(
+    Isolate* isolate,
+    uint16_t bitmask,
+    uint16_t compare_value) {
+  return NewBitmaskCompare(isolate, bitmask, compare_value, this);
+}
+
+
+Local<DeclaredAccessorDescriptor> RawOperationDescriptor::NewBitmaskCompare32(
+    Isolate* isolate,
+    uint32_t bitmask,
+    uint32_t compare_value) {
+  return NewBitmaskCompare(isolate, bitmask, compare_value, this);
+}
+
+
 Local<TypeSwitch> TypeSwitch::New(Handle<FunctionTemplate> type) {
   Handle<FunctionTemplate> types[1] = { type };
   return TypeSwitch::New(1, types);
@@ -988,7 +1069,6 @@
 
 Local<TypeSwitch> TypeSwitch::New(int argc, Handle<FunctionTemplate> types[]) {
   i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::TypeSwitch::New()");
   LOG_API(isolate, "TypeSwitch::New");
   ENTER_V8(isolate);
   i::Handle<i::FixedArray> vector = isolate->factory()->NewFixedArray(argc);
@@ -1011,23 +1091,22 @@
   i::Handle<i::TypeSwitchInfo> info = Utils::OpenHandle(this);
   i::FixedArray* types = i::FixedArray::cast(info->types());
   for (int i = 0; i < types->length(); i++) {
-    if (obj->IsInstanceOf(i::FunctionTemplateInfo::cast(types->get(i))))
+    if (i::FunctionTemplateInfo::cast(types->get(i))->IsTemplateFor(*obj))
       return i + 1;
   }
   return 0;
 }
 
 
-#define SET_FIELD_WRAPPED(obj, setter, cdata) do {    \
-    i::Handle<i::Object> foreign = FromCData(cdata);  \
-    (obj)->setter(*foreign);                          \
+#define SET_FIELD_WRAPPED(obj, setter, cdata) do {                      \
+    i::Handle<i::Object> foreign = FromCData(obj->GetIsolate(), cdata); \
+    (obj)->setter(*foreign);                                            \
   } while (false)
 
 
-void FunctionTemplate::SetCallHandler(InvocationCallback callback,
+void FunctionTemplate::SetCallHandler(FunctionCallback callback,
                                       v8::Handle<Value> data) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::SetCallHandler()")) return;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::Struct> struct_obj =
@@ -1035,82 +1114,99 @@
   i::Handle<i::CallHandlerInfo> obj =
       i::Handle<i::CallHandlerInfo>::cast(struct_obj);
   SET_FIELD_WRAPPED(obj, set_callback, callback);
-  if (data.IsEmpty()) data = v8::Undefined();
+  if (data.IsEmpty()) {
+    data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+  }
   obj->set_data(*Utils::OpenHandle(*data));
   Utils::OpenHandle(this)->set_call_code(*obj);
 }
 
 
-static i::Handle<i::AccessorInfo> MakeAccessorInfo(
-      v8::Handle<String> name,
-      AccessorGetter getter,
-      AccessorSetter setter,
-      v8::Handle<Value> data,
-      v8::AccessControl settings,
-      v8::PropertyAttribute attributes) {
-  i::Handle<i::AccessorInfo> obj = FACTORY->NewAccessorInfo();
-  ASSERT(getter != NULL);
-  SET_FIELD_WRAPPED(obj, set_getter, getter);
-  SET_FIELD_WRAPPED(obj, set_setter, setter);
-  if (data.IsEmpty()) data = v8::Undefined();
-  obj->set_data(*Utils::OpenHandle(*data));
+static i::Handle<i::AccessorInfo> SetAccessorInfoProperties(
+    i::Handle<i::AccessorInfo> obj,
+    v8::Handle<Name> name,
+    v8::AccessControl settings,
+    v8::PropertyAttribute attributes,
+    v8::Handle<AccessorSignature> signature) {
   obj->set_name(*Utils::OpenHandle(*name));
   if (settings & ALL_CAN_READ) obj->set_all_can_read(true);
   if (settings & ALL_CAN_WRITE) obj->set_all_can_write(true);
-  if (settings & PROHIBITS_OVERWRITING) obj->set_prohibits_overwriting(true);
   obj->set_property_attributes(static_cast<PropertyAttributes>(attributes));
+  if (!signature.IsEmpty()) {
+    obj->set_expected_receiver_type(*Utils::OpenHandle(*signature));
+  }
   return obj;
 }
 
 
-void FunctionTemplate::AddInstancePropertyAccessor(
-      v8::Handle<String> name,
-      AccessorGetter getter,
-      AccessorSetter setter,
-      v8::Handle<Value> data,
-      v8::AccessControl settings,
-      v8::PropertyAttribute attributes) {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate,
-                  "v8::FunctionTemplate::AddInstancePropertyAccessor()")) {
-    return;
+template<typename Getter, typename Setter>
+static i::Handle<i::AccessorInfo> MakeAccessorInfo(
+    v8::Handle<Name> name,
+    Getter getter,
+    Setter setter,
+    v8::Handle<Value> data,
+    v8::AccessControl settings,
+    v8::PropertyAttribute attributes,
+    v8::Handle<AccessorSignature> signature) {
+  i::Isolate* isolate = Utils::OpenHandle(*name)->GetIsolate();
+  i::Handle<i::ExecutableAccessorInfo> obj =
+      isolate->factory()->NewExecutableAccessorInfo();
+  SET_FIELD_WRAPPED(obj, set_getter, getter);
+  SET_FIELD_WRAPPED(obj, set_setter, setter);
+  if (data.IsEmpty()) {
+    data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
   }
-  ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
+  obj->set_data(*Utils::OpenHandle(*data));
+  return SetAccessorInfoProperties(obj, name, settings, attributes, signature);
+}
 
-  i::Handle<i::AccessorInfo> obj = MakeAccessorInfo(name,
-                                                    getter, setter, data,
-                                                    settings, attributes);
-  i::Handle<i::Object> list(Utils::OpenHandle(this)->property_accessors());
-  if (list->IsUndefined()) {
-    list = NeanderArray().value();
-    Utils::OpenHandle(this)->set_property_accessors(*list);
-  }
-  NeanderArray array(list);
-  array.add(obj);
+
+static i::Handle<i::AccessorInfo> MakeAccessorInfo(
+    v8::Handle<Name> name,
+    v8::Handle<v8::DeclaredAccessorDescriptor> descriptor,
+    void* setter_ignored,
+    void* data_ignored,
+    v8::AccessControl settings,
+    v8::PropertyAttribute attributes,
+    v8::Handle<AccessorSignature> signature) {
+  i::Isolate* isolate = Utils::OpenHandle(*name)->GetIsolate();
+  if (descriptor.IsEmpty()) return i::Handle<i::DeclaredAccessorInfo>();
+  i::Handle<i::DeclaredAccessorInfo> obj =
+      isolate->factory()->NewDeclaredAccessorInfo();
+  obj->set_descriptor(*Utils::OpenHandle(*descriptor));
+  return SetAccessorInfoProperties(obj, name, settings, attributes, signature);
 }
 
 
 Local<ObjectTemplate> FunctionTemplate::InstanceTemplate() {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::InstanceTemplate()")
-      || EmptyCheck("v8::FunctionTemplate::InstanceTemplate()", this))
+  i::Handle<i::FunctionTemplateInfo> handle = Utils::OpenHandle(this, true);
+  if (!Utils::ApiCheck(!handle.is_null(),
+                       "v8::FunctionTemplate::InstanceTemplate()",
+                       "Reading from empty handle")) {
     return Local<ObjectTemplate>();
-  ENTER_V8(isolate);
-  if (Utils::OpenHandle(this)->instance_template()->IsUndefined()) {
-    Local<ObjectTemplate> templ =
-        ObjectTemplate::New(v8::Handle<FunctionTemplate>(this));
-    Utils::OpenHandle(this)->set_instance_template(*Utils::OpenHandle(*templ));
   }
-  i::Handle<i::ObjectTemplateInfo> result(i::ObjectTemplateInfo::cast(
-        Utils::OpenHandle(this)->instance_template()));
+  i::Isolate* isolate = handle->GetIsolate();
+  ENTER_V8(isolate);
+  if (handle->instance_template()->IsUndefined()) {
+    Local<ObjectTemplate> templ =
+        ObjectTemplate::New(isolate, ToApiHandle<FunctionTemplate>(handle));
+    handle->set_instance_template(*Utils::OpenHandle(*templ));
+  }
+  i::Handle<i::ObjectTemplateInfo> result(
+      i::ObjectTemplateInfo::cast(handle->instance_template()));
   return Utils::ToLocal(result);
 }
 
 
+void FunctionTemplate::SetLength(int length) {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ENTER_V8(isolate);
+  Utils::OpenHandle(this)->set_length(length);
+}
+
+
 void FunctionTemplate::SetClassName(Handle<String> name) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::SetClassName()")) return;
   ENTER_V8(isolate);
   Utils::OpenHandle(this)->set_class_name(*Utils::OpenHandle(*name));
 }
@@ -1118,9 +1214,6 @@
 
 void FunctionTemplate::SetHiddenPrototype(bool value) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::SetHiddenPrototype()")) {
-    return;
-  }
   ENTER_V8(isolate);
   Utils::OpenHandle(this)->set_hidden_prototype(value);
 }
@@ -1128,112 +1221,34 @@
 
 void FunctionTemplate::ReadOnlyPrototype() {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::FunctionTemplate::SetPrototypeAttributes()")) {
-    return;
-  }
   ENTER_V8(isolate);
   Utils::OpenHandle(this)->set_read_only_prototype(true);
 }
 
 
-void FunctionTemplate::SetNamedInstancePropertyHandler(
-      NamedPropertyGetter getter,
-      NamedPropertySetter setter,
-      NamedPropertyQuery query,
-      NamedPropertyDeleter remover,
-      NamedPropertyEnumerator enumerator,
-      Handle<Value> data) {
+void FunctionTemplate::RemovePrototype() {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate,
-                  "v8::FunctionTemplate::SetNamedInstancePropertyHandler()")) {
-    return;
-  }
   ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  i::Handle<i::Struct> struct_obj =
-      isolate->factory()->NewStruct(i::INTERCEPTOR_INFO_TYPE);
-  i::Handle<i::InterceptorInfo> obj =
-      i::Handle<i::InterceptorInfo>::cast(struct_obj);
-
-  if (getter != 0) SET_FIELD_WRAPPED(obj, set_getter, getter);
-  if (setter != 0) SET_FIELD_WRAPPED(obj, set_setter, setter);
-  if (query != 0) SET_FIELD_WRAPPED(obj, set_query, query);
-  if (remover != 0) SET_FIELD_WRAPPED(obj, set_deleter, remover);
-  if (enumerator != 0) SET_FIELD_WRAPPED(obj, set_enumerator, enumerator);
-
-  if (data.IsEmpty()) data = v8::Undefined();
-  obj->set_data(*Utils::OpenHandle(*data));
-  Utils::OpenHandle(this)->set_named_property_handler(*obj);
-}
-
-
-void FunctionTemplate::SetIndexedInstancePropertyHandler(
-      IndexedPropertyGetter getter,
-      IndexedPropertySetter setter,
-      IndexedPropertyQuery query,
-      IndexedPropertyDeleter remover,
-      IndexedPropertyEnumerator enumerator,
-      Handle<Value> data) {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate,
-        "v8::FunctionTemplate::SetIndexedInstancePropertyHandler()")) {
-    return;
-  }
-  ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  i::Handle<i::Struct> struct_obj =
-      isolate->factory()->NewStruct(i::INTERCEPTOR_INFO_TYPE);
-  i::Handle<i::InterceptorInfo> obj =
-      i::Handle<i::InterceptorInfo>::cast(struct_obj);
-
-  if (getter != 0) SET_FIELD_WRAPPED(obj, set_getter, getter);
-  if (setter != 0) SET_FIELD_WRAPPED(obj, set_setter, setter);
-  if (query != 0) SET_FIELD_WRAPPED(obj, set_query, query);
-  if (remover != 0) SET_FIELD_WRAPPED(obj, set_deleter, remover);
-  if (enumerator != 0) SET_FIELD_WRAPPED(obj, set_enumerator, enumerator);
-
-  if (data.IsEmpty()) data = v8::Undefined();
-  obj->set_data(*Utils::OpenHandle(*data));
-  Utils::OpenHandle(this)->set_indexed_property_handler(*obj);
-}
-
-
-void FunctionTemplate::SetInstanceCallAsFunctionHandler(
-      InvocationCallback callback,
-      Handle<Value> data) {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate,
-                  "v8::FunctionTemplate::SetInstanceCallAsFunctionHandler()")) {
-    return;
-  }
-  ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  i::Handle<i::Struct> struct_obj =
-      isolate->factory()->NewStruct(i::CALL_HANDLER_INFO_TYPE);
-  i::Handle<i::CallHandlerInfo> obj =
-      i::Handle<i::CallHandlerInfo>::cast(struct_obj);
-  SET_FIELD_WRAPPED(obj, set_callback, callback);
-  if (data.IsEmpty()) data = v8::Undefined();
-  obj->set_data(*Utils::OpenHandle(*data));
-  Utils::OpenHandle(this)->set_instance_call_handler(*obj);
+  Utils::OpenHandle(this)->set_remove_prototype(true);
 }
 
 
 // --- O b j e c t T e m p l a t e ---
 
 
+Local<ObjectTemplate> ObjectTemplate::New(Isolate* isolate) {
+  return New(reinterpret_cast<i::Isolate*>(isolate), Local<FunctionTemplate>());
+}
+
+
 Local<ObjectTemplate> ObjectTemplate::New() {
-  return New(Local<FunctionTemplate>());
+  return New(i::Isolate::Current(), Local<FunctionTemplate>());
 }
 
 
 Local<ObjectTemplate> ObjectTemplate::New(
-      v8::Handle<FunctionTemplate> constructor) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::New()")) {
-    return Local<ObjectTemplate>();
-  }
-  EnsureInitializedForIsolate(isolate, "v8::ObjectTemplate::New()");
+    i::Isolate* isolate,
+    v8::Handle<FunctionTemplate> constructor) {
   LOG_API(isolate, "ObjectTemplate::New");
   ENTER_V8(isolate);
   i::Handle<i::Struct> struct_obj =
@@ -1250,70 +1265,173 @@
 
 // Ensure that the object template has a constructor.  If no
 // constructor is available we create one.
-static void EnsureConstructor(ObjectTemplate* object_template) {
-  if (Utils::OpenHandle(object_template)->constructor()->IsUndefined()) {
-    Local<FunctionTemplate> templ = FunctionTemplate::New();
-    i::Handle<i::FunctionTemplateInfo> constructor = Utils::OpenHandle(*templ);
-    constructor->set_instance_template(*Utils::OpenHandle(object_template));
-    Utils::OpenHandle(object_template)->set_constructor(*constructor);
+static i::Handle<i::FunctionTemplateInfo> EnsureConstructor(
+    i::Isolate* isolate,
+    ObjectTemplate* object_template) {
+  i::Object* obj = Utils::OpenHandle(object_template)->constructor();
+  if (!obj ->IsUndefined()) {
+    i::FunctionTemplateInfo* info = i::FunctionTemplateInfo::cast(obj);
+    return i::Handle<i::FunctionTemplateInfo>(info, isolate);
   }
+  Local<FunctionTemplate> templ =
+      FunctionTemplate::New(reinterpret_cast<Isolate*>(isolate));
+  i::Handle<i::FunctionTemplateInfo> constructor = Utils::OpenHandle(*templ);
+  constructor->set_instance_template(*Utils::OpenHandle(object_template));
+  Utils::OpenHandle(object_template)->set_constructor(*constructor);
+  return constructor;
+}
+
+
+static inline void AddPropertyToTemplate(
+    i::Handle<i::TemplateInfo> info,
+    i::Handle<i::AccessorInfo> obj) {
+  i::Isolate* isolate = info->GetIsolate();
+  i::Handle<i::Object> list(info->property_accessors(), isolate);
+  if (list->IsUndefined()) {
+    list = NeanderArray(isolate).value();
+    info->set_property_accessors(*list);
+  }
+  NeanderArray array(list);
+  array.add(obj);
+}
+
+
+static inline i::Handle<i::TemplateInfo> GetTemplateInfo(
+    i::Isolate* isolate,
+    Template* template_obj) {
+  return Utils::OpenHandle(template_obj);
+}
+
+
+// TODO(dcarney): remove this with ObjectTemplate::SetAccessor
+static inline i::Handle<i::TemplateInfo> GetTemplateInfo(
+    i::Isolate* isolate,
+    ObjectTemplate* object_template) {
+  EnsureConstructor(isolate, object_template);
+  return Utils::OpenHandle(object_template);
+}
+
+
+template<typename Getter, typename Setter, typename Data, typename Template>
+static bool TemplateSetAccessor(
+    Template* template_obj,
+    v8::Local<Name> name,
+    Getter getter,
+    Setter setter,
+    Data data,
+    AccessControl settings,
+    PropertyAttribute attribute,
+    v8::Local<AccessorSignature> signature) {
+  i::Isolate* isolate = Utils::OpenHandle(template_obj)->GetIsolate();
+  ENTER_V8(isolate);
+  i::HandleScope scope(isolate);
+  i::Handle<i::AccessorInfo> obj = MakeAccessorInfo(
+      name, getter, setter, data, settings, attribute, signature);
+  if (obj.is_null()) return false;
+  i::Handle<i::TemplateInfo> info = GetTemplateInfo(isolate, template_obj);
+  AddPropertyToTemplate(info, obj);
+  return true;
+}
+
+
+bool Template::SetDeclaredAccessor(
+    Local<Name> name,
+    Local<DeclaredAccessorDescriptor> descriptor,
+    PropertyAttribute attribute,
+    Local<AccessorSignature> signature,
+    AccessControl settings) {
+  void* null = NULL;
+  return TemplateSetAccessor(
+      this, name, descriptor, null, null, settings, attribute, signature);
+}
+
+
+void Template::SetNativeDataProperty(v8::Local<String> name,
+                                     AccessorGetterCallback getter,
+                                     AccessorSetterCallback setter,
+                                     v8::Handle<Value> data,
+                                     PropertyAttribute attribute,
+                                     v8::Local<AccessorSignature> signature,
+                                     AccessControl settings) {
+  TemplateSetAccessor(
+      this, name, getter, setter, data, settings, attribute, signature);
+}
+
+
+void Template::SetNativeDataProperty(v8::Local<Name> name,
+                                     AccessorNameGetterCallback getter,
+                                     AccessorNameSetterCallback setter,
+                                     v8::Handle<Value> data,
+                                     PropertyAttribute attribute,
+                                     v8::Local<AccessorSignature> signature,
+                                     AccessControl settings) {
+  TemplateSetAccessor(
+      this, name, getter, setter, data, settings, attribute, signature);
 }
 
 
 void ObjectTemplate::SetAccessor(v8::Handle<String> name,
-                                 AccessorGetter getter,
-                                 AccessorSetter setter,
+                                 AccessorGetterCallback getter,
+                                 AccessorSetterCallback setter,
                                  v8::Handle<Value> data,
                                  AccessControl settings,
-                                 PropertyAttribute attribute) {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::SetAccessor()")) return;
-  ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  EnsureConstructor(this);
-  i::FunctionTemplateInfo* constructor =
-      i::FunctionTemplateInfo::cast(Utils::OpenHandle(this)->constructor());
-  i::Handle<i::FunctionTemplateInfo> cons(constructor);
-  Utils::ToLocal(cons)->AddInstancePropertyAccessor(name,
-                                                    getter,
-                                                    setter,
-                                                    data,
-                                                    settings,
-                                                    attribute);
+                                 PropertyAttribute attribute,
+                                 v8::Handle<AccessorSignature> signature) {
+  TemplateSetAccessor(
+      this, name, getter, setter, data, settings, attribute, signature);
 }
 
 
-void ObjectTemplate::SetNamedPropertyHandler(NamedPropertyGetter getter,
-                                             NamedPropertySetter setter,
-                                             NamedPropertyQuery query,
-                                             NamedPropertyDeleter remover,
-                                             NamedPropertyEnumerator enumerator,
-                                             Handle<Value> data) {
+void ObjectTemplate::SetAccessor(v8::Handle<Name> name,
+                                 AccessorNameGetterCallback getter,
+                                 AccessorNameSetterCallback setter,
+                                 v8::Handle<Value> data,
+                                 AccessControl settings,
+                                 PropertyAttribute attribute,
+                                 v8::Handle<AccessorSignature> signature) {
+  TemplateSetAccessor(
+      this, name, getter, setter, data, settings, attribute, signature);
+}
+
+
+void ObjectTemplate::SetNamedPropertyHandler(
+    NamedPropertyGetterCallback getter,
+    NamedPropertySetterCallback setter,
+    NamedPropertyQueryCallback query,
+    NamedPropertyDeleterCallback remover,
+    NamedPropertyEnumeratorCallback enumerator,
+    Handle<Value> data) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::SetNamedPropertyHandler()")) {
-    return;
-  }
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  EnsureConstructor(this);
-  i::FunctionTemplateInfo* constructor =
-      i::FunctionTemplateInfo::cast(Utils::OpenHandle(this)->constructor());
+  EnsureConstructor(isolate, this);
+  i::FunctionTemplateInfo* constructor = i::FunctionTemplateInfo::cast(
+      Utils::OpenHandle(this)->constructor());
   i::Handle<i::FunctionTemplateInfo> cons(constructor);
-  Utils::ToLocal(cons)->SetNamedInstancePropertyHandler(getter,
-                                                        setter,
-                                                        query,
-                                                        remover,
-                                                        enumerator,
-                                                        data);
+  i::Handle<i::Struct> struct_obj =
+      isolate->factory()->NewStruct(i::INTERCEPTOR_INFO_TYPE);
+  i::Handle<i::InterceptorInfo> obj =
+      i::Handle<i::InterceptorInfo>::cast(struct_obj);
+
+  if (getter != 0) SET_FIELD_WRAPPED(obj, set_getter, getter);
+  if (setter != 0) SET_FIELD_WRAPPED(obj, set_setter, setter);
+  if (query != 0) SET_FIELD_WRAPPED(obj, set_query, query);
+  if (remover != 0) SET_FIELD_WRAPPED(obj, set_deleter, remover);
+  if (enumerator != 0) SET_FIELD_WRAPPED(obj, set_enumerator, enumerator);
+
+  if (data.IsEmpty()) {
+    data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+  }
+  obj->set_data(*Utils::OpenHandle(*data));
+  cons->set_named_property_handler(*obj);
 }
 
 
 void ObjectTemplate::MarkAsUndetectable() {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::MarkAsUndetectable()")) return;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  EnsureConstructor(this);
+  EnsureConstructor(isolate, this);
   i::FunctionTemplateInfo* constructor =
       i::FunctionTemplateInfo::cast(Utils::OpenHandle(this)->constructor());
   i::Handle<i::FunctionTemplateInfo> cons(constructor);
@@ -1322,17 +1440,14 @@
 
 
 void ObjectTemplate::SetAccessCheckCallbacks(
-      NamedSecurityCallback named_callback,
-      IndexedSecurityCallback indexed_callback,
-      Handle<Value> data,
-      bool turned_on_by_default) {
+    NamedSecurityCallback named_callback,
+    IndexedSecurityCallback indexed_callback,
+    Handle<Value> data,
+    bool turned_on_by_default) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::SetAccessCheckCallbacks()")) {
-    return;
-  }
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  EnsureConstructor(this);
+  EnsureConstructor(isolate, this);
 
   i::Handle<i::Struct> struct_info =
       isolate->factory()->NewStruct(i::ACCESS_CHECK_INFO_TYPE);
@@ -1342,7 +1457,9 @@
   SET_FIELD_WRAPPED(info, set_named_callback, named_callback);
   SET_FIELD_WRAPPED(info, set_indexed_callback, indexed_callback);
 
-  if (data.IsEmpty()) data = v8::Undefined();
+  if (data.IsEmpty()) {
+    data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+  }
   info->set_data(*Utils::OpenHandle(*data));
 
   i::FunctionTemplateInfo* constructor =
@@ -1354,65 +1471,70 @@
 
 
 void ObjectTemplate::SetIndexedPropertyHandler(
-      IndexedPropertyGetter getter,
-      IndexedPropertySetter setter,
-      IndexedPropertyQuery query,
-      IndexedPropertyDeleter remover,
-      IndexedPropertyEnumerator enumerator,
-      Handle<Value> data) {
+    IndexedPropertyGetterCallback getter,
+    IndexedPropertySetterCallback setter,
+    IndexedPropertyQueryCallback query,
+    IndexedPropertyDeleterCallback remover,
+    IndexedPropertyEnumeratorCallback enumerator,
+    Handle<Value> data) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::SetIndexedPropertyHandler()")) {
-    return;
-  }
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  EnsureConstructor(this);
-  i::FunctionTemplateInfo* constructor =
-      i::FunctionTemplateInfo::cast(Utils::OpenHandle(this)->constructor());
+  EnsureConstructor(isolate, this);
+  i::FunctionTemplateInfo* constructor = i::FunctionTemplateInfo::cast(
+      Utils::OpenHandle(this)->constructor());
   i::Handle<i::FunctionTemplateInfo> cons(constructor);
-  Utils::ToLocal(cons)->SetIndexedInstancePropertyHandler(getter,
-                                                          setter,
-                                                          query,
-                                                          remover,
-                                                          enumerator,
-                                                          data);
+  i::Handle<i::Struct> struct_obj =
+      isolate->factory()->NewStruct(i::INTERCEPTOR_INFO_TYPE);
+  i::Handle<i::InterceptorInfo> obj =
+      i::Handle<i::InterceptorInfo>::cast(struct_obj);
+
+  if (getter != 0) SET_FIELD_WRAPPED(obj, set_getter, getter);
+  if (setter != 0) SET_FIELD_WRAPPED(obj, set_setter, setter);
+  if (query != 0) SET_FIELD_WRAPPED(obj, set_query, query);
+  if (remover != 0) SET_FIELD_WRAPPED(obj, set_deleter, remover);
+  if (enumerator != 0) SET_FIELD_WRAPPED(obj, set_enumerator, enumerator);
+
+  if (data.IsEmpty()) {
+    data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+  }
+  obj->set_data(*Utils::OpenHandle(*data));
+  cons->set_indexed_property_handler(*obj);
 }
 
 
-void ObjectTemplate::SetCallAsFunctionHandler(InvocationCallback callback,
+void ObjectTemplate::SetCallAsFunctionHandler(FunctionCallback callback,
                                               Handle<Value> data) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate,
-                  "v8::ObjectTemplate::SetCallAsFunctionHandler()")) {
-    return;
-  }
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  EnsureConstructor(this);
-  i::FunctionTemplateInfo* constructor =
-      i::FunctionTemplateInfo::cast(Utils::OpenHandle(this)->constructor());
+  EnsureConstructor(isolate, this);
+  i::FunctionTemplateInfo* constructor = i::FunctionTemplateInfo::cast(
+      Utils::OpenHandle(this)->constructor());
   i::Handle<i::FunctionTemplateInfo> cons(constructor);
-  Utils::ToLocal(cons)->SetInstanceCallAsFunctionHandler(callback, data);
+  i::Handle<i::Struct> struct_obj =
+      isolate->factory()->NewStruct(i::CALL_HANDLER_INFO_TYPE);
+  i::Handle<i::CallHandlerInfo> obj =
+      i::Handle<i::CallHandlerInfo>::cast(struct_obj);
+  SET_FIELD_WRAPPED(obj, set_callback, callback);
+  if (data.IsEmpty()) {
+    data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+  }
+  obj->set_data(*Utils::OpenHandle(*data));
+  cons->set_instance_call_handler(*obj);
 }
 
 
 int ObjectTemplate::InternalFieldCount() {
-  if (IsDeadCheck(Utils::OpenHandle(this)->GetIsolate(),
-                  "v8::ObjectTemplate::InternalFieldCount()")) {
-    return 0;
-  }
   return i::Smi::cast(Utils::OpenHandle(this)->internal_field_count())->value();
 }
 
 
 void ObjectTemplate::SetInternalFieldCount(int value) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::ObjectTemplate::SetInternalFieldCount()")) {
-    return;
-  }
-  if (!ApiCheck(i::Smi::IsValid(value),
-                "v8::ObjectTemplate::SetInternalFieldCount()",
-                "Invalid internal field count")) {
+  if (!Utils::ApiCheck(i::Smi::IsValid(value),
+                       "v8::ObjectTemplate::SetInternalFieldCount()",
+                       "Invalid internal field count")) {
     return;
   }
   ENTER_V8(isolate);
@@ -1420,223 +1542,361 @@
     // The internal field count is set by the constructor function's
     // construct code, so we ensure that there is a constructor
     // function to do the setting.
-    EnsureConstructor(this);
+    EnsureConstructor(isolate, this);
   }
   Utils::OpenHandle(this)->set_internal_field_count(i::Smi::FromInt(value));
 }
 
 
-// --- S c r i p t D a t a ---
+// --- S c r i p t s ---
 
 
-ScriptData* ScriptData::PreCompile(const char* input, int length) {
-  i::Utf8ToUtf16CharacterStream stream(
-      reinterpret_cast<const unsigned char*>(input), length);
-  return i::ParserApi::PreParse(&stream, NULL, i::FLAG_harmony_scoping);
+// Internally, UnboundScript is a SharedFunctionInfo, and Script is a
+// JSFunction.
+
+ScriptCompiler::CachedData::CachedData(const uint8_t* data_, int length_,
+                                       BufferPolicy buffer_policy_)
+    : data(data_), length(length_), buffer_policy(buffer_policy_) {}
+
+
+ScriptCompiler::CachedData::~CachedData() {
+  if (buffer_policy == BufferOwned) {
+    delete[] data;
+  }
 }
 
 
-ScriptData* ScriptData::PreCompile(v8::Handle<String> source) {
-  i::Handle<i::String> str = Utils::OpenHandle(*source);
-  if (str->IsExternalTwoByteString()) {
-    i::ExternalTwoByteStringUtf16CharacterStream stream(
-      i::Handle<i::ExternalTwoByteString>::cast(str), 0, str->length());
-    return i::ParserApi::PreParse(&stream, NULL, i::FLAG_harmony_scoping);
+ScriptCompiler::StreamedSource::StreamedSource(ExternalSourceStream* stream,
+                                               Encoding encoding)
+    : impl_(new i::StreamedSource(stream, encoding)) {}
+
+
+ScriptCompiler::StreamedSource::~StreamedSource() { delete impl_; }
+
+
+const ScriptCompiler::CachedData*
+ScriptCompiler::StreamedSource::GetCachedData() const {
+  return impl_->cached_data.get();
+}
+
+
+Local<Script> UnboundScript::BindToCurrentContext() {
+  i::Handle<i::HeapObject> obj =
+      i::Handle<i::HeapObject>::cast(Utils::OpenHandle(this));
+  i::Handle<i::SharedFunctionInfo>
+      function_info(i::SharedFunctionInfo::cast(*obj), obj->GetIsolate());
+  i::Handle<i::JSFunction> function =
+      obj->GetIsolate()->factory()->NewFunctionFromSharedFunctionInfo(
+          function_info, obj->GetIsolate()->global_context());
+  return ToApiHandle<Script>(function);
+}
+
+
+int UnboundScript::GetId() {
+  i::Handle<i::HeapObject> obj =
+      i::Handle<i::HeapObject>::cast(Utils::OpenHandle(this));
+  i::Isolate* isolate = obj->GetIsolate();
+  ON_BAILOUT(isolate, "v8::UnboundScript::GetId()", return -1);
+  LOG_API(isolate, "v8::UnboundScript::GetId");
+  {
+    i::HandleScope scope(isolate);
+    i::Handle<i::SharedFunctionInfo> function_info(
+        i::SharedFunctionInfo::cast(*obj));
+    i::Handle<i::Script> script(i::Script::cast(function_info->script()));
+    return script->id()->value();
+  }
+}
+
+
+int UnboundScript::GetLineNumber(int code_pos) {
+  i::Handle<i::SharedFunctionInfo> obj =
+      i::Handle<i::SharedFunctionInfo>::cast(Utils::OpenHandle(this));
+  i::Isolate* isolate = obj->GetIsolate();
+  ON_BAILOUT(isolate, "v8::UnboundScript::GetLineNumber()", return -1);
+  LOG_API(isolate, "UnboundScript::GetLineNumber");
+  if (obj->script()->IsScript()) {
+    i::Handle<i::Script> script(i::Script::cast(obj->script()));
+    return i::Script::GetLineNumber(script, code_pos);
   } else {
-    i::GenericStringUtf16CharacterStream stream(str, 0, str->length());
-    return i::ParserApi::PreParse(&stream, NULL, i::FLAG_harmony_scoping);
+    return -1;
   }
 }
 
 
-ScriptData* ScriptData::New(const char* data, int length) {
-  // Return an empty ScriptData if the length is obviously invalid.
-  if (length % sizeof(unsigned) != 0) {
-    return new i::ScriptDataImpl();
+Handle<Value> UnboundScript::GetScriptName() {
+  i::Handle<i::SharedFunctionInfo> obj =
+      i::Handle<i::SharedFunctionInfo>::cast(Utils::OpenHandle(this));
+  i::Isolate* isolate = obj->GetIsolate();
+  ON_BAILOUT(isolate, "v8::UnboundScript::GetName()",
+             return Handle<String>());
+  LOG_API(isolate, "UnboundScript::GetName");
+  if (obj->script()->IsScript()) {
+    i::Object* name = i::Script::cast(obj->script())->name();
+    return Utils::ToLocal(i::Handle<i::Object>(name, isolate));
+  } else {
+    return Handle<String>();
   }
+}
 
-  // Copy the data to ensure it is properly aligned.
-  int deserialized_data_length = length / sizeof(unsigned);
-  // If aligned, don't create a copy of the data.
-  if (reinterpret_cast<intptr_t>(data) % sizeof(unsigned) == 0) {
-    return new i::ScriptDataImpl(data, length);
+
+Handle<Value> UnboundScript::GetSourceURL() {
+  i::Handle<i::SharedFunctionInfo> obj =
+      i::Handle<i::SharedFunctionInfo>::cast(Utils::OpenHandle(this));
+  i::Isolate* isolate = obj->GetIsolate();
+  ON_BAILOUT(isolate, "v8::UnboundScript::GetSourceURL()",
+             return Handle<String>());
+  LOG_API(isolate, "UnboundScript::GetSourceURL");
+  if (obj->script()->IsScript()) {
+    i::Object* url = i::Script::cast(obj->script())->source_url();
+    return Utils::ToLocal(i::Handle<i::Object>(url, isolate));
+  } else {
+    return Handle<String>();
   }
-  // Copy the data to align it.
-  unsigned* deserialized_data = i::NewArray<unsigned>(deserialized_data_length);
-  i::OS::MemCopy(deserialized_data, data, length);
-
-  return new i::ScriptDataImpl(
-      i::Vector<unsigned>(deserialized_data, deserialized_data_length));
 }
 
 
-// --- S c r i p t ---
-
-
-Local<Script> Script::New(v8::Handle<String> source,
-                          v8::ScriptOrigin* origin,
-                          v8::ScriptData* pre_data,
-                          v8::Handle<String> script_data) {
-  i::Isolate* isolate = i::Isolate::Current();
-  ON_BAILOUT(isolate, "v8::Script::New()", return Local<Script>());
-  LOG_API(isolate, "Script::New");
-  ENTER_V8(isolate);
-  i::SharedFunctionInfo* raw_result = NULL;
-  { i::HandleScope scope(isolate);
-    i::Handle<i::String> str = Utils::OpenHandle(*source);
-    i::Handle<i::Object> name_obj;
-    int line_offset = 0;
-    int column_offset = 0;
-    if (origin != NULL) {
-      if (!origin->ResourceName().IsEmpty()) {
-        name_obj = Utils::OpenHandle(*origin->ResourceName());
-      }
-      if (!origin->ResourceLineOffset().IsEmpty()) {
-        line_offset = static_cast<int>(origin->ResourceLineOffset()->Value());
-      }
-      if (!origin->ResourceColumnOffset().IsEmpty()) {
-        column_offset =
-            static_cast<int>(origin->ResourceColumnOffset()->Value());
-      }
-    }
-    EXCEPTION_PREAMBLE(isolate);
-    i::ScriptDataImpl* pre_data_impl =
-        static_cast<i::ScriptDataImpl*>(pre_data);
-    // We assert that the pre-data is sane, even though we can actually
-    // handle it if it turns out not to be in release mode.
-    ASSERT(pre_data_impl == NULL || pre_data_impl->SanityCheck());
-    // If the pre-data isn't sane we simply ignore it
-    if (pre_data_impl != NULL && !pre_data_impl->SanityCheck()) {
-      pre_data_impl = NULL;
-    }
-    i::Handle<i::SharedFunctionInfo> result =
-      i::Compiler::Compile(str,
-                           name_obj,
-                           line_offset,
-                           column_offset,
-                           NULL,
-                           pre_data_impl,
-                           Utils::OpenHandle(*script_data),
-                           i::NOT_NATIVES_CODE);
-    has_pending_exception = result.is_null();
-    EXCEPTION_BAILOUT_CHECK(isolate, Local<Script>());
-    raw_result = *result;
+Handle<Value> UnboundScript::GetSourceMappingURL() {
+  i::Handle<i::SharedFunctionInfo> obj =
+      i::Handle<i::SharedFunctionInfo>::cast(Utils::OpenHandle(this));
+  i::Isolate* isolate = obj->GetIsolate();
+  ON_BAILOUT(isolate, "v8::UnboundScript::GetSourceMappingURL()",
+             return Handle<String>());
+  LOG_API(isolate, "UnboundScript::GetSourceMappingURL");
+  if (obj->script()->IsScript()) {
+    i::Object* url = i::Script::cast(obj->script())->source_mapping_url();
+    return Utils::ToLocal(i::Handle<i::Object>(url, isolate));
+  } else {
+    return Handle<String>();
   }
-  i::Handle<i::SharedFunctionInfo> result(raw_result, isolate);
-  return Local<Script>(ToApi<Script>(result));
-}
-
-
-Local<Script> Script::New(v8::Handle<String> source,
-                          v8::Handle<Value> file_name) {
-  ScriptOrigin origin(file_name);
-  return New(source, &origin);
-}
-
-
-Local<Script> Script::Compile(v8::Handle<String> source,
-                              v8::ScriptOrigin* origin,
-                              v8::ScriptData* pre_data,
-                              v8::Handle<String> script_data) {
-  i::Isolate* isolate = i::Isolate::Current();
-  ON_BAILOUT(isolate, "v8::Script::Compile()", return Local<Script>());
-  LOG_API(isolate, "Script::Compile");
-  ENTER_V8(isolate);
-  Local<Script> generic = New(source, origin, pre_data, script_data);
-  if (generic.IsEmpty())
-    return generic;
-  i::Handle<i::Object> obj = Utils::OpenHandle(*generic);
-  i::Handle<i::SharedFunctionInfo> function =
-      i::Handle<i::SharedFunctionInfo>(i::SharedFunctionInfo::cast(*obj));
-  i::Handle<i::JSFunction> result =
-      isolate->factory()->NewFunctionFromSharedFunctionInfo(
-          function,
-          isolate->global_context());
-  return Local<Script>(ToApi<Script>(result));
-}
-
-
-Local<Script> Script::Compile(v8::Handle<String> source,
-                              v8::Handle<Value> file_name,
-                              v8::Handle<String> script_data) {
-  ScriptOrigin origin(file_name);
-  return Compile(source, &origin, 0, script_data);
 }
 
 
 Local<Value> Script::Run() {
-  i::Isolate* isolate = i::Isolate::Current();
+  i::Handle<i::Object> obj = Utils::OpenHandle(this, true);
+  // If execution is terminating, Compile(..)->Run() requires this
+  // check.
+  if (obj.is_null()) return Local<Value>();
+  i::Isolate* isolate = i::Handle<i::HeapObject>::cast(obj)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Script::Run()", return Local<Value>());
   LOG_API(isolate, "Script::Run");
   ENTER_V8(isolate);
-  i::Object* raw_result = NULL;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::Object> obj = Utils::OpenHandle(this);
-    i::Handle<i::JSFunction> fun;
-    if (obj->IsSharedFunctionInfo()) {
-      i::Handle<i::SharedFunctionInfo>
-          function_info(i::SharedFunctionInfo::cast(*obj), isolate);
-      fun = isolate->factory()->NewFunctionFromSharedFunctionInfo(
-          function_info, isolate->global_context());
-    } else {
-      fun = i::Handle<i::JSFunction>(i::JSFunction::cast(*obj), isolate);
+  i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
+  i::HandleScope scope(isolate);
+  i::Handle<i::JSFunction> fun = i::Handle<i::JSFunction>::cast(obj);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> receiver(isolate->global_proxy(), isolate);
+  i::Handle<i::Object> result;
+  has_pending_exception = !i::Execution::Call(
+      isolate, fun, receiver, 0, NULL).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<Value>());
+  return Utils::ToLocal(scope.CloseAndEscape(result));
+}
+
+
+Local<UnboundScript> Script::GetUnboundScript() {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this);
+  return ToApiHandle<UnboundScript>(
+      i::Handle<i::SharedFunctionInfo>(i::JSFunction::cast(*obj)->shared()));
+}
+
+
+Local<UnboundScript> ScriptCompiler::CompileUnbound(
+    Isolate* v8_isolate,
+    Source* source,
+    CompileOptions options) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  ON_BAILOUT(isolate, "v8::ScriptCompiler::CompileUnbound()",
+             return Local<UnboundScript>());
+
+  // Support the old API for a transition period:
+  // - kProduceToCache -> kProduceParserCache
+  // - kNoCompileOptions + cached_data != NULL -> kConsumeParserCache
+  if (options == kProduceDataToCache) {
+    options = kProduceParserCache;
+  } else if (options == kNoCompileOptions && source->cached_data) {
+    options = kConsumeParserCache;
+  }
+
+  i::ScriptData* script_data = NULL;
+  if (options == kConsumeParserCache || options == kConsumeCodeCache) {
+    DCHECK(source->cached_data);
+    // ScriptData takes care of pointer-aligning the data.
+    script_data = new i::ScriptData(source->cached_data->data,
+                                    source->cached_data->length);
+  }
+
+  i::Handle<i::String> str = Utils::OpenHandle(*(source->source_string));
+  LOG_API(isolate, "ScriptCompiler::CompileUnbound");
+  ENTER_V8(isolate);
+  i::SharedFunctionInfo* raw_result = NULL;
+  { i::HandleScope scope(isolate);
+    i::Handle<i::Object> name_obj;
+    int line_offset = 0;
+    int column_offset = 0;
+    bool is_shared_cross_origin = false;
+    if (!source->resource_name.IsEmpty()) {
+      name_obj = Utils::OpenHandle(*(source->resource_name));
+    }
+    if (!source->resource_line_offset.IsEmpty()) {
+      line_offset = static_cast<int>(source->resource_line_offset->Value());
+    }
+    if (!source->resource_column_offset.IsEmpty()) {
+      column_offset =
+          static_cast<int>(source->resource_column_offset->Value());
+    }
+    if (!source->resource_is_shared_cross_origin.IsEmpty()) {
+      v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate);
+      is_shared_cross_origin =
+          source->resource_is_shared_cross_origin == v8::True(v8_isolate);
     }
     EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> receiver(
-        isolate->context()->global_proxy(), isolate);
-    i::Handle<i::Object> result =
-        i::Execution::Call(fun, receiver, 0, NULL, &has_pending_exception);
-    EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<Value>());
+    i::Handle<i::SharedFunctionInfo> result = i::Compiler::CompileScript(
+        str, name_obj, line_offset, column_offset, is_shared_cross_origin,
+        isolate->global_context(), NULL, &script_data, options,
+        i::NOT_NATIVES_CODE);
+    has_pending_exception = result.is_null();
+    if (has_pending_exception && script_data != NULL) {
+      // This case won't happen during normal operation; we have compiled
+      // successfully and produced cached data, and but the second compilation
+      // of the same source code fails.
+      delete script_data;
+      script_data = NULL;
+    }
+    EXCEPTION_BAILOUT_CHECK(isolate, Local<UnboundScript>());
     raw_result = *result;
+
+    if ((options == kProduceParserCache || options == kProduceCodeCache) &&
+        script_data != NULL) {
+      // script_data now contains the data that was generated. source will
+      // take the ownership.
+      source->cached_data = new CachedData(
+          script_data->data(), script_data->length(), CachedData::BufferOwned);
+      script_data->ReleaseDataOwnership();
+    }
+    delete script_data;
   }
-  i::Handle<i::Object> result(raw_result, isolate);
-  return Utils::ToLocal(result);
+  i::Handle<i::SharedFunctionInfo> result(raw_result, isolate);
+  return ToApiHandle<UnboundScript>(result);
 }
 
 
-static i::Handle<i::SharedFunctionInfo> OpenScript(Script* script) {
-  i::Handle<i::Object> obj = Utils::OpenHandle(script);
-  i::Handle<i::SharedFunctionInfo> result;
-  if (obj->IsSharedFunctionInfo()) {
-    result =
-        i::Handle<i::SharedFunctionInfo>(i::SharedFunctionInfo::cast(*obj));
-  } else {
-    result =
-        i::Handle<i::SharedFunctionInfo>(i::JSFunction::cast(*obj)->shared());
-  }
-  return result;
+Local<Script> ScriptCompiler::Compile(
+    Isolate* v8_isolate,
+    Source* source,
+    CompileOptions options) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  ON_BAILOUT(isolate, "v8::ScriptCompiler::Compile()", return Local<Script>());
+  LOG_API(isolate, "ScriptCompiler::CompiletBound()");
+  ENTER_V8(isolate);
+  Local<UnboundScript> generic = CompileUnbound(v8_isolate, source, options);
+  if (generic.IsEmpty()) return Local<Script>();
+  return generic->BindToCurrentContext();
 }
 
 
-Local<Value> Script::Id() {
-  i::Isolate* isolate = i::Isolate::Current();
-  ON_BAILOUT(isolate, "v8::Script::Id()", return Local<Value>());
-  LOG_API(isolate, "Script::Id");
-  i::Object* raw_id = NULL;
+ScriptCompiler::ScriptStreamingTask* ScriptCompiler::StartStreamingScript(
+    Isolate* v8_isolate, StreamedSource* source, CompileOptions options) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  if (!isolate->global_context().is_null() &&
+      !isolate->global_context()->IsNativeContext()) {
+    // The context chain is non-trivial, and constructing the corresponding
+    // non-trivial Scope chain outside the V8 heap is not implemented. Don't
+    // stream the script. This will only occur if Harmony scoping is enabled and
+    // a previous script has introduced "let" or "const" variables. TODO(marja):
+    // Implement externalizing ScopeInfos and constructing non-trivial Scope
+    // chains independent of the V8 heap so that we can stream also in this
+    // case.
+    return NULL;
+  }
+  return new i::BackgroundParsingTask(source->impl(), options,
+                                      i::FLAG_stack_size, isolate);
+}
+
+
+Local<Script> ScriptCompiler::Compile(Isolate* v8_isolate,
+                                      StreamedSource* v8_source,
+                                      Handle<String> full_source_string,
+                                      const ScriptOrigin& origin) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  i::StreamedSource* source = v8_source->impl();
+  ON_BAILOUT(isolate, "v8::ScriptCompiler::Compile()", return Local<Script>());
+  LOG_API(isolate, "ScriptCompiler::Compile()");
+  ENTER_V8(isolate);
+  i::SharedFunctionInfo* raw_result = NULL;
+
   {
     i::HandleScope scope(isolate);
-    i::Handle<i::SharedFunctionInfo> function_info = OpenScript(this);
-    i::Handle<i::Script> script(i::Script::cast(function_info->script()));
-    i::Handle<i::Object> id(script->id());
-    raw_id = *id;
+    i::Handle<i::String> str = Utils::OpenHandle(*(full_source_string));
+    i::Handle<i::Script> script = isolate->factory()->NewScript(str);
+    if (!origin.ResourceName().IsEmpty()) {
+      script->set_name(*Utils::OpenHandle(*(origin.ResourceName())));
+    }
+    if (!origin.ResourceLineOffset().IsEmpty()) {
+      script->set_line_offset(i::Smi::FromInt(
+          static_cast<int>(origin.ResourceLineOffset()->Value())));
+    }
+    if (!origin.ResourceColumnOffset().IsEmpty()) {
+      script->set_column_offset(i::Smi::FromInt(
+          static_cast<int>(origin.ResourceColumnOffset()->Value())));
+    }
+    if (!origin.ResourceIsSharedCrossOrigin().IsEmpty()) {
+      script->set_is_shared_cross_origin(origin.ResourceIsSharedCrossOrigin() ==
+                                         v8::True(v8_isolate));
+    }
+    source->info->set_script(script);
+    source->info->SetContext(isolate->global_context());
+
+    EXCEPTION_PREAMBLE(isolate);
+
+    // Do the parsing tasks which need to be done on the main thread. This will
+    // also handle parse errors.
+    source->parser->Internalize();
+
+    i::Handle<i::SharedFunctionInfo> result =
+        i::Handle<i::SharedFunctionInfo>::null();
+    if (source->info->function() != NULL) {
+      // Parsing has succeeded.
+      result =
+          i::Compiler::CompileStreamedScript(source->info.get(), str->length());
+    }
+    has_pending_exception = result.is_null();
+    if (has_pending_exception) isolate->ReportPendingMessages();
+    EXCEPTION_BAILOUT_CHECK(isolate, Local<Script>());
+
+    raw_result = *result;
+    // The Handle<Script> will go out of scope soon; make sure CompilationInfo
+    // doesn't point to it.
+    source->info->set_script(i::Handle<i::Script>());
+  }  // HandleScope goes out of scope.
+  i::Handle<i::SharedFunctionInfo> result(raw_result, isolate);
+  Local<UnboundScript> generic = ToApiHandle<UnboundScript>(result);
+  if (generic.IsEmpty()) {
+    return Local<Script>();
   }
-  i::Handle<i::Object> id(raw_id);
-  return Utils::ToLocal(id);
+  return generic->BindToCurrentContext();
 }
 
 
-void Script::SetData(v8::Handle<String> data) {
-  i::Isolate* isolate = i::Isolate::Current();
-  ON_BAILOUT(isolate, "v8::Script::SetData()", return);
-  LOG_API(isolate, "Script::SetData");
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::SharedFunctionInfo> function_info = OpenScript(this);
-    i::Handle<i::Object> raw_data = Utils::OpenHandle(*data);
-    i::Handle<i::Script> script(i::Script::cast(function_info->script()));
-    script->set_data(*raw_data);
+Local<Script> Script::Compile(v8::Handle<String> source,
+                              v8::ScriptOrigin* origin) {
+  i::Handle<i::String> str = Utils::OpenHandle(*source);
+  if (origin) {
+    ScriptCompiler::Source script_source(source, *origin);
+    return ScriptCompiler::Compile(
+        reinterpret_cast<v8::Isolate*>(str->GetIsolate()),
+        &script_source);
   }
+  ScriptCompiler::Source script_source(source);
+  return ScriptCompiler::Compile(
+      reinterpret_cast<v8::Isolate*>(str->GetIsolate()),
+      &script_source);
+}
+
+
+Local<Script> Script::Compile(v8::Handle<String> source,
+                              v8::Handle<String> file_name) {
+  ScriptOrigin origin(file_name);
+  return Compile(source, &origin);
 }
 
 
@@ -1645,26 +1905,48 @@
 
 v8::TryCatch::TryCatch()
     : isolate_(i::Isolate::Current()),
-      next_(isolate_->try_catch_handler_address()),
-      exception_(isolate_->heap()->the_hole_value()),
-      message_(i::Smi::FromInt(0)),
+      next_(isolate_->try_catch_handler()),
       is_verbose_(false),
       can_continue_(true),
       capture_message_(true),
-      rethrow_(false) {
+      rethrow_(false),
+      has_terminated_(false) {
+  ResetInternal();
+  // Special handling for simulators which have a separate JS stack.
+  js_stack_comparable_address_ =
+      reinterpret_cast<void*>(v8::internal::SimulatorStack::RegisterCTryCatch(
+          v8::internal::GetCurrentStackPosition()));
   isolate_->RegisterTryCatchHandler(this);
 }
 
 
 v8::TryCatch::~TryCatch() {
-  ASSERT(isolate_ == i::Isolate::Current());
+  DCHECK(isolate_ == i::Isolate::Current());
   if (rethrow_) {
-    v8::HandleScope scope;
-    v8::Local<v8::Value> exc = v8::Local<v8::Value>::New(Exception());
+    v8::Isolate* isolate = reinterpret_cast<Isolate*>(isolate_);
+    v8::HandleScope scope(isolate);
+    v8::Local<v8::Value> exc = v8::Local<v8::Value>::New(isolate, Exception());
+    if (HasCaught() && capture_message_) {
+      // If an exception was caught and rethrow_ is indicated, the saved
+      // message, script, and location need to be restored to Isolate TLS
+      // for reuse.  capture_message_ needs to be disabled so that DoThrow()
+      // does not create a new message.
+      isolate_->thread_local_top()->rethrowing_message_ = true;
+      isolate_->RestorePendingMessageFromTryCatch(this);
+    }
     isolate_->UnregisterTryCatchHandler(this);
-    v8::ThrowException(exc);
+    v8::internal::SimulatorStack::UnregisterCTryCatch();
+    reinterpret_cast<Isolate*>(isolate_)->ThrowException(exc);
+    DCHECK(!isolate_->thread_local_top()->rethrowing_message_);
   } else {
+    if (HasCaught() && isolate_->has_scheduled_exception()) {
+      // If an exception was caught but is still scheduled because no API call
+      // promoted it, then it is canceled to prevent it from being propagated.
+      // Note that this will not cancel termination exceptions.
+      isolate_->CancelScheduledExceptionFromTryCatch(this);
+    }
     isolate_->UnregisterTryCatchHandler(this);
+    v8::internal::SimulatorStack::UnregisterCTryCatch();
   }
 }
 
@@ -1679,15 +1961,20 @@
 }
 
 
+bool v8::TryCatch::HasTerminated() const {
+  return has_terminated_;
+}
+
+
 v8::Handle<v8::Value> v8::TryCatch::ReThrow() {
   if (!HasCaught()) return v8::Local<v8::Value>();
   rethrow_ = true;
-  return v8::Undefined();
+  return v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate_));
 }
 
 
 v8::Local<Value> v8::TryCatch::Exception() const {
-  ASSERT(isolate_ == i::Isolate::Current());
+  DCHECK(isolate_ == i::Isolate::Current());
   if (HasCaught()) {
     // Check for out of memory exception.
     i::Object* exception = reinterpret_cast<i::Object*>(exception_);
@@ -1699,16 +1986,22 @@
 
 
 v8::Local<Value> v8::TryCatch::StackTrace() const {
-  ASSERT(isolate_ == i::Isolate::Current());
+  DCHECK(isolate_ == i::Isolate::Current());
   if (HasCaught()) {
     i::Object* raw_obj = reinterpret_cast<i::Object*>(exception_);
     if (!raw_obj->IsJSObject()) return v8::Local<Value>();
     i::HandleScope scope(isolate_);
     i::Handle<i::JSObject> obj(i::JSObject::cast(raw_obj), isolate_);
-    i::Handle<i::String> name = isolate_->factory()->LookupAsciiSymbol("stack");
-    if (!obj->HasProperty(*name)) return v8::Local<Value>();
-    i::Handle<i::Object> value = i::GetProperty(obj, name);
-    if (value.is_null()) return v8::Local<Value>();
+    i::Handle<i::String> name = isolate_->factory()->stack_string();
+    EXCEPTION_PREAMBLE(isolate_);
+    Maybe<bool> maybe = i::JSReceiver::HasProperty(obj, name);
+    has_pending_exception = !maybe.has_value;
+    EXCEPTION_BAILOUT_CHECK(isolate_, v8::Local<Value>());
+    if (!maybe.value) return v8::Local<Value>();
+    i::Handle<i::Object> value;
+    if (!i::Object::GetProperty(obj, name).ToHandle(&value)) {
+      return v8::Local<Value>();
+    }
     return v8::Utils::ToLocal(scope.CloseAndEscape(value));
   } else {
     return v8::Local<Value>();
@@ -1717,9 +2010,10 @@
 
 
 v8::Local<v8::Message> v8::TryCatch::Message() const {
-  ASSERT(isolate_ == i::Isolate::Current());
-  if (HasCaught() && message_ != i::Smi::FromInt(0)) {
-    i::Object* message = reinterpret_cast<i::Object*>(message_);
+  DCHECK(isolate_ == i::Isolate::Current());
+  i::Object* message = reinterpret_cast<i::Object*>(message_obj_);
+  DCHECK(message->IsJSMessageObject() || message->IsTheHole());
+  if (HasCaught() && !message->IsTheHole()) {
     return v8::Utils::MessageToLocal(i::Handle<i::Object>(message, isolate_));
   } else {
     return v8::Local<v8::Message>();
@@ -1728,9 +2022,24 @@
 
 
 void v8::TryCatch::Reset() {
-  ASSERT(isolate_ == i::Isolate::Current());
-  exception_ = isolate_->heap()->the_hole_value();
-  message_ = i::Smi::FromInt(0);
+  DCHECK(isolate_ == i::Isolate::Current());
+  if (!rethrow_ && HasCaught() && isolate_->has_scheduled_exception()) {
+    // If an exception was caught but is still scheduled because no API call
+    // promoted it, then it is canceled to prevent it from being propagated.
+    // Note that this will not cancel termination exceptions.
+    isolate_->CancelScheduledExceptionFromTryCatch(this);
+  }
+  ResetInternal();
+}
+
+
+void v8::TryCatch::ResetInternal() {
+  i::Object* the_hole = isolate_->heap()->the_hole_value();
+  exception_ = the_hole;
+  message_obj_ = the_hole;
+  message_script_ = the_hole;
+  message_start_pos_ = 0;
+  message_end_pos_ = 0;
 }
 
 
@@ -1751,91 +2060,77 @@
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Message::Get()", return Local<String>());
   ENTER_V8(isolate);
-  HandleScope scope;
+  EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  i::Handle<i::String> raw_result = i::MessageHandler::GetMessage(obj);
+  i::Handle<i::String> raw_result = i::MessageHandler::GetMessage(isolate, obj);
   Local<String> result = Utils::ToLocal(raw_result);
-  return scope.Close(result);
+  return scope.Escape(result);
+}
+
+
+ScriptOrigin Message::GetScriptOrigin() const {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  i::Handle<i::JSMessageObject> message =
+      i::Handle<i::JSMessageObject>::cast(Utils::OpenHandle(this));
+  i::Handle<i::Object> script_wraper =
+      i::Handle<i::Object>(message->script(), isolate);
+  i::Handle<i::JSValue> script_value =
+      i::Handle<i::JSValue>::cast(script_wraper);
+  i::Handle<i::Script> script(i::Script::cast(script_value->value()));
+  i::Handle<i::Object> scriptName(i::Script::GetNameOrSourceURL(script));
+  v8::Isolate* v8_isolate =
+      reinterpret_cast<v8::Isolate*>(script->GetIsolate());
+  v8::ScriptOrigin origin(
+      Utils::ToLocal(scriptName),
+      v8::Integer::New(v8_isolate, script->line_offset()->value()),
+      v8::Integer::New(v8_isolate, script->column_offset()->value()),
+      Handle<Boolean>(),
+      v8::Integer::New(v8_isolate, script->id()->value()));
+  return origin;
 }
 
 
 v8::Handle<Value> Message::GetScriptResourceName() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetScriptResourceName()")) {
-    return Local<String>();
-  }
-  ENTER_V8(isolate);
-  HandleScope scope;
-  i::Handle<i::JSMessageObject> message =
-      i::Handle<i::JSMessageObject>::cast(Utils::OpenHandle(this));
-  // Return this.script.name.
-  i::Handle<i::JSValue> script =
-      i::Handle<i::JSValue>::cast(i::Handle<i::Object>(message->script()));
-  i::Handle<i::Object> resource_name(i::Script::cast(script->value())->name());
-  return scope.Close(Utils::ToLocal(resource_name));
-}
-
-
-v8::Handle<Value> Message::GetScriptData() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetScriptResourceData()")) {
-    return Local<Value>();
-  }
-  ENTER_V8(isolate);
-  HandleScope scope;
-  i::Handle<i::JSMessageObject> message =
-      i::Handle<i::JSMessageObject>::cast(Utils::OpenHandle(this));
-  // Return this.script.data.
-  i::Handle<i::JSValue> script =
-      i::Handle<i::JSValue>::cast(i::Handle<i::Object>(message->script()));
-  i::Handle<i::Object> data(i::Script::cast(script->value())->data());
-  return scope.Close(Utils::ToLocal(data));
+  return GetScriptOrigin().ResourceName();
 }
 
 
 v8::Handle<v8::StackTrace> Message::GetStackTrace() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetStackTrace()")) {
-    return Local<v8::StackTrace>();
-  }
   ENTER_V8(isolate);
-  HandleScope scope;
+  EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
   i::Handle<i::JSMessageObject> message =
       i::Handle<i::JSMessageObject>::cast(Utils::OpenHandle(this));
-  i::Handle<i::Object> stackFramesObj(message->stack_frames());
+  i::Handle<i::Object> stackFramesObj(message->stack_frames(), isolate);
   if (!stackFramesObj->IsJSArray()) return v8::Handle<v8::StackTrace>();
   i::Handle<i::JSArray> stackTrace =
       i::Handle<i::JSArray>::cast(stackFramesObj);
-  return scope.Close(Utils::StackTraceToLocal(stackTrace));
+  return scope.Escape(Utils::StackTraceToLocal(stackTrace));
 }
 
 
-static i::Handle<i::Object> CallV8HeapFunction(const char* name,
-                                               i::Handle<i::Object> recv,
-                                               int argc,
-                                               i::Handle<i::Object> argv[],
-                                               bool* has_pending_exception) {
+MUST_USE_RESULT static i::MaybeHandle<i::Object> CallV8HeapFunction(
+    const char* name,
+    i::Handle<i::Object> recv,
+    int argc,
+    i::Handle<i::Object> argv[]) {
   i::Isolate* isolate = i::Isolate::Current();
-  i::Handle<i::String> fmt_str = isolate->factory()->LookupAsciiSymbol(name);
-  i::Object* object_fun =
-      isolate->js_builtins_object()->GetPropertyNoExceptionThrown(*fmt_str);
-  i::Handle<i::JSFunction> fun =
-      i::Handle<i::JSFunction>(i::JSFunction::cast(object_fun));
-  i::Handle<i::Object> value =
-      i::Execution::Call(fun, recv, argc, argv, has_pending_exception);
-  return value;
+  i::Handle<i::Object> object_fun =
+      i::Object::GetProperty(
+          isolate, isolate->js_builtins_object(), name).ToHandleChecked();
+  i::Handle<i::JSFunction> fun = i::Handle<i::JSFunction>::cast(object_fun);
+  return i::Execution::Call(isolate, fun, recv, argc, argv);
 }
 
 
-static i::Handle<i::Object> CallV8HeapFunction(const char* name,
-                                               i::Handle<i::Object> data,
-                                               bool* has_pending_exception) {
+MUST_USE_RESULT static i::MaybeHandle<i::Object> CallV8HeapFunction(
+    const char* name,
+    i::Handle<i::Object> data) {
   i::Handle<i::Object> argv[] = { data };
   return CallV8HeapFunction(name,
                             i::Isolate::Current()->js_builtins_object(),
-                            ARRAY_SIZE(argv),
-                            argv,
-                            has_pending_exception);
+                            arraysize(argv),
+                            argv);
 }
 
 
@@ -1846,9 +2141,9 @@
   i::HandleScope scope(isolate);
 
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> result = CallV8HeapFunction("GetLineNumber",
-                                                   Utils::OpenHandle(this),
-                                                   &has_pending_exception);
+  i::Handle<i::Object> result;
+  has_pending_exception = !CallV8HeapFunction(
+      "GetLineNumber", Utils::OpenHandle(this)).ToHandle(&result);
   EXCEPTION_BAILOUT_CHECK(isolate, 0);
   return static_cast<int>(result->Number());
 }
@@ -1856,7 +2151,6 @@
 
 int Message::GetStartPosition() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetStartPosition()")) return 0;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSMessageObject> message =
@@ -1867,7 +2161,6 @@
 
 int Message::GetEndPosition() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetEndPosition()")) return 0;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSMessageObject> message =
@@ -1878,17 +2171,14 @@
 
 int Message::GetStartColumn() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetStartColumn()")) {
-    return kNoColumnInfo;
-  }
+  ON_BAILOUT(isolate, "v8::Message::GetStartColumn()", return kNoColumnInfo);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> data_obj = Utils::OpenHandle(this);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> start_col_obj = CallV8HeapFunction(
-      "GetPositionInLine",
-      data_obj,
-      &has_pending_exception);
+  i::Handle<i::Object> start_col_obj;
+  has_pending_exception = !CallV8HeapFunction(
+      "GetPositionInLine", data_obj).ToHandle(&start_col_obj);
   EXCEPTION_BAILOUT_CHECK(isolate, 0);
   return static_cast<int>(start_col_obj->Number());
 }
@@ -1896,15 +2186,14 @@
 
 int Message::GetEndColumn() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Message::GetEndColumn()")) return kNoColumnInfo;
+  ON_BAILOUT(isolate, "v8::Message::GetEndColumn()", return kNoColumnInfo);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> data_obj = Utils::OpenHandle(this);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> start_col_obj = CallV8HeapFunction(
-      "GetPositionInLine",
-      data_obj,
-      &has_pending_exception);
+  i::Handle<i::Object> start_col_obj;
+  has_pending_exception = !CallV8HeapFunction(
+      "GetPositionInLine", data_obj).ToHandle(&start_col_obj);
   EXCEPTION_BAILOUT_CHECK(isolate, 0);
   i::Handle<i::JSMessageObject> message =
       i::Handle<i::JSMessageObject>::cast(data_obj);
@@ -1914,29 +2203,41 @@
 }
 
 
+bool Message::IsSharedCrossOrigin() const {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ENTER_V8(isolate);
+  i::HandleScope scope(isolate);
+  i::Handle<i::JSMessageObject> message =
+      i::Handle<i::JSMessageObject>::cast(Utils::OpenHandle(this));
+  i::Handle<i::JSValue> script =
+      i::Handle<i::JSValue>::cast(i::Handle<i::Object>(message->script(),
+                                                       isolate));
+  return i::Script::cast(script->value())->is_shared_cross_origin();
+}
+
+
 Local<String> Message::GetSourceLine() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Message::GetSourceLine()", return Local<String>());
   ENTER_V8(isolate);
-  HandleScope scope;
+  EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> result = CallV8HeapFunction("GetSourceLine",
-                                                   Utils::OpenHandle(this),
-                                                   &has_pending_exception);
+  i::Handle<i::Object> result;
+  has_pending_exception = !CallV8HeapFunction(
+      "GetSourceLine", Utils::OpenHandle(this)).ToHandle(&result);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::String>());
   if (result->IsString()) {
-    return scope.Close(Utils::ToLocal(i::Handle<i::String>::cast(result)));
+    return scope.Escape(Utils::ToLocal(i::Handle<i::String>::cast(result)));
   } else {
     return Local<String>();
   }
 }
 
 
-void Message::PrintCurrentStackTrace(FILE* out) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Message::PrintCurrentStackTrace()")) return;
-  ENTER_V8(isolate);
-  isolate->PrintCurrentStackTrace(out);
+void Message::PrintCurrentStackTrace(Isolate* isolate, FILE* out) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  ENTER_V8(i_isolate);
+  i_isolate->PrintCurrentStackTrace(out);
 }
 
 
@@ -1944,21 +2245,18 @@
 
 Local<StackFrame> StackTrace::GetFrame(uint32_t index) const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackTrace::GetFrame()")) {
-    return Local<StackFrame>();
-  }
   ENTER_V8(isolate);
-  HandleScope scope;
+  EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
   i::Handle<i::JSArray> self = Utils::OpenHandle(this);
-  i::Object* raw_object = self->GetElementNoExceptionThrown(index);
-  i::Handle<i::JSObject> obj(i::JSObject::cast(raw_object));
-  return scope.Close(Utils::StackFrameToLocal(obj));
+  i::Handle<i::Object> obj =
+      i::Object::GetElement(isolate, self, index).ToHandleChecked();
+  i::Handle<i::JSObject> jsobj = i::Handle<i::JSObject>::cast(obj);
+  return scope.Escape(Utils::StackFrameToLocal(jsobj));
 }
 
 
 int StackTrace::GetFrameCount() const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackTrace::GetFrameCount()")) return -1;
   ENTER_V8(isolate);
   return i::Smi::cast(Utils::OpenHandle(this)->length())->value();
 }
@@ -1966,287 +2264,291 @@
 
 Local<Array> StackTrace::AsArray() {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackTrace::AsArray()")) Local<Array>();
   ENTER_V8(isolate);
   return Utils::ToLocal(Utils::OpenHandle(this));
 }
 
 
-Local<StackTrace> StackTrace::CurrentStackTrace(int frame_limit,
+Local<StackTrace> StackTrace::CurrentStackTrace(
+    Isolate* isolate,
+    int frame_limit,
     StackTraceOptions options) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::StackTrace::CurrentStackTrace()")) {
-    Local<StackTrace>();
-  }
-  ENTER_V8(isolate);
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  ENTER_V8(i_isolate);
+  // TODO(dcarney): remove when ScriptDebugServer is fixed.
+  options = static_cast<StackTraceOptions>(
+      static_cast<int>(options) | kExposeFramesAcrossSecurityOrigins);
   i::Handle<i::JSArray> stackTrace =
-      isolate->CaptureCurrentStackTrace(frame_limit, options);
+      i_isolate->CaptureCurrentStackTrace(frame_limit, options);
   return Utils::StackTraceToLocal(stackTrace);
 }
 
 
 // --- S t a c k F r a m e ---
 
-int StackFrame::GetLineNumber() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::GetLineNumber()")) {
-    return Message::kNoLineNumberInfo;
-  }
+static int getIntProperty(const StackFrame* f, const char* propertyName,
+                          int defaultValue) {
+  i::Isolate* isolate = Utils::OpenHandle(f)->GetIsolate();
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> line = GetProperty(self, "lineNumber");
-  if (!line->IsSmi()) {
-    return Message::kNoLineNumberInfo;
-  }
-  return i::Smi::cast(*line)->value();
+  i::Handle<i::JSObject> self = Utils::OpenHandle(f);
+  i::Handle<i::Object> obj =
+      i::Object::GetProperty(isolate, self, propertyName).ToHandleChecked();
+  return obj->IsSmi() ? i::Smi::cast(*obj)->value() : defaultValue;
+}
+
+
+int StackFrame::GetLineNumber() const {
+  return getIntProperty(this, "lineNumber", Message::kNoLineNumberInfo);
 }
 
 
 int StackFrame::GetColumn() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::GetColumn()")) {
-    return Message::kNoColumnInfo;
-  }
+  return getIntProperty(this, "column", Message::kNoColumnInfo);
+}
+
+
+int StackFrame::GetScriptId() const {
+  return getIntProperty(this, "scriptId", Message::kNoScriptIdInfo);
+}
+
+
+static Local<String> getStringProperty(const StackFrame* f,
+                                       const char* propertyName) {
+  i::Isolate* isolate = Utils::OpenHandle(f)->GetIsolate();
   ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> column = GetProperty(self, "column");
-  if (!column->IsSmi()) {
-    return Message::kNoColumnInfo;
-  }
-  return i::Smi::cast(*column)->value();
+  EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
+  i::Handle<i::JSObject> self = Utils::OpenHandle(f);
+  i::Handle<i::Object> obj =
+      i::Object::GetProperty(isolate, self, propertyName).ToHandleChecked();
+  return obj->IsString()
+             ? scope.Escape(Local<String>::Cast(Utils::ToLocal(obj)))
+             : Local<String>();
 }
 
 
 Local<String> StackFrame::GetScriptName() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::GetScriptName()")) {
-    return Local<String>();
-  }
-  ENTER_V8(isolate);
-  HandleScope scope;
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> name = GetProperty(self, "scriptName");
-  if (!name->IsString()) {
-    return Local<String>();
-  }
-  return scope.Close(Local<String>::Cast(Utils::ToLocal(name)));
+  return getStringProperty(this, "scriptName");
 }
 
 
 Local<String> StackFrame::GetScriptNameOrSourceURL() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::GetScriptNameOrSourceURL()")) {
-    return Local<String>();
-  }
-  ENTER_V8(isolate);
-  HandleScope scope;
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> name = GetProperty(self, "scriptNameOrSourceURL");
-  if (!name->IsString()) {
-    return Local<String>();
-  }
-  return scope.Close(Local<String>::Cast(Utils::ToLocal(name)));
+  return getStringProperty(this, "scriptNameOrSourceURL");
 }
 
 
 Local<String> StackFrame::GetFunctionName() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::GetFunctionName()")) {
-    return Local<String>();
-  }
-  ENTER_V8(isolate);
-  HandleScope scope;
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> name = GetProperty(self, "functionName");
-  if (!name->IsString()) {
-    return Local<String>();
-  }
-  return scope.Close(Local<String>::Cast(Utils::ToLocal(name)));
+  return getStringProperty(this, "functionName");
 }
 
 
-bool StackFrame::IsEval() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::IsEval()")) return false;
+static bool getBoolProperty(const StackFrame* f, const char* propertyName) {
+  i::Isolate* isolate = Utils::OpenHandle(f)->GetIsolate();
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> is_eval = GetProperty(self, "isEval");
-  return is_eval->IsTrue();
+  i::Handle<i::JSObject> self = Utils::OpenHandle(f);
+  i::Handle<i::Object> obj =
+      i::Object::GetProperty(isolate, self, propertyName).ToHandleChecked();
+  return obj->IsTrue();
 }
 
+bool StackFrame::IsEval() const { return getBoolProperty(this, "isEval"); }
+
 
 bool StackFrame::IsConstructor() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::StackFrame::IsConstructor()")) return false;
+  return getBoolProperty(this, "isConstructor");
+}
+
+
+// --- J S O N ---
+
+Local<Value> JSON::Parse(Local<String> json_string) {
+  i::Handle<i::String> string = Utils::OpenHandle(*json_string);
+  i::Isolate* isolate = string->GetIsolate();
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> is_constructor = GetProperty(self, "isConstructor");
-  return is_constructor->IsTrue();
+  i::Handle<i::String> source = i::String::Flatten(string);
+  EXCEPTION_PREAMBLE(isolate);
+  i::MaybeHandle<i::Object> maybe_result =
+      source->IsSeqOneByteString() ? i::JsonParser<true>::Parse(source)
+                                   : i::JsonParser<false>::Parse(source);
+  i::Handle<i::Object> result;
+  has_pending_exception = !maybe_result.ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<Object>());
+  return Utils::ToLocal(
+      i::Handle<i::Object>::cast(scope.CloseAndEscape(result)));
 }
 
 
 // --- D a t a ---
 
-bool Value::IsUndefined() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsUndefined()")) {
-    return false;
-  }
-  return Utils::OpenHandle(this)->IsUndefined();
+bool Value::FullIsUndefined() const {
+  bool result = Utils::OpenHandle(this)->IsUndefined();
+  DCHECK_EQ(result, QuickIsUndefined());
+  return result;
 }
 
 
-bool Value::IsNull() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsNull()")) return false;
-  return Utils::OpenHandle(this)->IsNull();
+bool Value::FullIsNull() const {
+  bool result = Utils::OpenHandle(this)->IsNull();
+  DCHECK_EQ(result, QuickIsNull());
+  return result;
 }
 
 
 bool Value::IsTrue() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsTrue()")) return false;
   return Utils::OpenHandle(this)->IsTrue();
 }
 
 
 bool Value::IsFalse() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsFalse()")) return false;
   return Utils::OpenHandle(this)->IsFalse();
 }
 
 
 bool Value::IsFunction() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsFunction()")) {
-    return false;
-  }
   return Utils::OpenHandle(this)->IsJSFunction();
 }
 
 
+bool Value::IsName() const {
+  return Utils::OpenHandle(this)->IsName();
+}
+
+
 bool Value::FullIsString() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsString()")) return false;
   bool result = Utils::OpenHandle(this)->IsString();
-  ASSERT_EQ(result, QuickIsString());
+  DCHECK_EQ(result, QuickIsString());
   return result;
 }
 
 
+bool Value::IsSymbol() const {
+  return Utils::OpenHandle(this)->IsSymbol();
+}
+
+
 bool Value::IsArray() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsArray()")) return false;
   return Utils::OpenHandle(this)->IsJSArray();
 }
 
 
+bool Value::IsArrayBuffer() const {
+  return Utils::OpenHandle(this)->IsJSArrayBuffer();
+}
+
+
+bool Value::IsArrayBufferView() const {
+  return Utils::OpenHandle(this)->IsJSArrayBufferView();
+}
+
+
+bool Value::IsTypedArray() const {
+  return Utils::OpenHandle(this)->IsJSTypedArray();
+}
+
+
+#define VALUE_IS_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)            \
+  bool Value::Is##Type##Array() const {                                    \
+    i::Handle<i::Object> obj = Utils::OpenHandle(this);                    \
+    return obj->IsJSTypedArray() &&                                        \
+           i::JSTypedArray::cast(*obj)->type() == kExternal##Type##Array;  \
+  }
+
+TYPED_ARRAYS(VALUE_IS_TYPED_ARRAY)
+
+#undef VALUE_IS_TYPED_ARRAY
+
+
+bool Value::IsDataView() const {
+  return Utils::OpenHandle(this)->IsJSDataView();
+}
+
+
 bool Value::IsObject() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsObject()")) return false;
   return Utils::OpenHandle(this)->IsJSObject();
 }
 
 
 bool Value::IsNumber() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsNumber()")) return false;
   return Utils::OpenHandle(this)->IsNumber();
 }
 
 
-bool Value::IsBoolean() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsBoolean()")) {
-    return false;
+#define VALUE_IS_SPECIFIC_TYPE(Type, Class)                            \
+  bool Value::Is##Type() const {                                       \
+    i::Handle<i::Object> obj = Utils::OpenHandle(this);                \
+    if (!obj->IsHeapObject()) return false;                            \
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();     \
+    return obj->HasSpecificClassOf(isolate->heap()->Class##_string()); \
   }
+
+VALUE_IS_SPECIFIC_TYPE(ArgumentsObject, Arguments)
+VALUE_IS_SPECIFIC_TYPE(BooleanObject, Boolean)
+VALUE_IS_SPECIFIC_TYPE(NumberObject, Number)
+VALUE_IS_SPECIFIC_TYPE(StringObject, String)
+VALUE_IS_SPECIFIC_TYPE(SymbolObject, Symbol)
+VALUE_IS_SPECIFIC_TYPE(Date, Date)
+VALUE_IS_SPECIFIC_TYPE(Map, Map)
+VALUE_IS_SPECIFIC_TYPE(Set, Set)
+VALUE_IS_SPECIFIC_TYPE(WeakMap, WeakMap)
+VALUE_IS_SPECIFIC_TYPE(WeakSet, WeakSet)
+
+#undef VALUE_IS_SPECIFIC_TYPE
+
+
+bool Value::IsBoolean() const {
   return Utils::OpenHandle(this)->IsBoolean();
 }
 
 
 bool Value::IsExternal() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsExternal()")) {
-    return false;
-  }
-  return Utils::OpenHandle(this)->IsForeign();
+  return Utils::OpenHandle(this)->IsExternal();
 }
 
 
 bool Value::IsInt32() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsInt32()")) return false;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsSmi()) return true;
   if (obj->IsNumber()) {
-    double value = obj->Number();
-    static const i::DoubleRepresentation minus_zero(-0.0);
-    i::DoubleRepresentation rep(value);
-    if (rep.bits == minus_zero.bits) {
-      return false;
-    }
-    return i::FastI2D(i::FastD2I(value)) == value;
+    return i::IsInt32Double(obj->Number());
   }
   return false;
 }
 
 
 bool Value::IsUint32() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsUint32()")) return false;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsSmi()) return i::Smi::cast(*obj)->value() >= 0;
   if (obj->IsNumber()) {
     double value = obj->Number();
-    static const i::DoubleRepresentation minus_zero(-0.0);
-    i::DoubleRepresentation rep(value);
-    if (rep.bits == minus_zero.bits) {
-      return false;
-    }
-    return i::FastUI2D(i::FastD2UI(value)) == value;
+    return !i::IsMinusZero(value) &&
+        value >= 0 &&
+        value <= i::kMaxUInt32 &&
+        value == i::FastUI2D(i::FastD2UI(value));
   }
   return false;
 }
 
 
-bool Value::IsDate() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::IsDate()")) return false;
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  return obj->HasSpecificClassOf(isolate->heap()->Date_symbol());
-}
-
-
-bool Value::IsStringObject() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::IsStringObject()")) return false;
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  return obj->HasSpecificClassOf(isolate->heap()->String_symbol());
-}
-
-
-bool Value::IsNumberObject() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::IsNumberObject()")) return false;
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  return obj->HasSpecificClassOf(isolate->heap()->Number_symbol());
-}
-
-
-static i::Object* LookupBuiltin(i::Isolate* isolate,
-                                const char* builtin_name) {
-  i::Handle<i::String> symbol =
-      isolate->factory()->LookupAsciiSymbol(builtin_name);
-  i::Handle<i::JSBuiltinsObject> builtins = isolate->js_builtins_object();
-  return builtins->GetPropertyNoExceptionThrown(*symbol);
-}
-
-
 static bool CheckConstructor(i::Isolate* isolate,
                              i::Handle<i::JSObject> obj,
                              const char* class_name) {
-  return obj->map()->constructor() == LookupBuiltin(isolate, class_name);
+  i::Handle<i::Object> constr(obj->map()->constructor(), isolate);
+  if (!constr->IsJSFunction()) return false;
+  i::Handle<i::JSFunction> func = i::Handle<i::JSFunction>::cast(constr);
+  return func->shared()->native() && constr.is_identical_to(
+      i::Object::GetProperty(isolate,
+                             isolate->js_builtins_object(),
+                             class_name).ToHandleChecked());
 }
 
 
 bool Value::IsNativeError() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::IsNativeError()")) return false;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsJSObject()) {
     i::Handle<i::JSObject> js_obj(i::JSObject::cast(*obj));
+    i::Isolate* isolate = js_obj->GetIsolate();
     return CheckConstructor(isolate, js_obj, "$Error") ||
         CheckConstructor(isolate, js_obj, "$EvalError") ||
         CheckConstructor(isolate, js_obj, "$RangeError") ||
@@ -2260,16 +2562,7 @@
 }
 
 
-bool Value::IsBooleanObject() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::IsBooleanObject()")) return false;
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  return obj->HasSpecificClassOf(isolate->heap()->Boolean_symbol());
-}
-
-
 bool Value::IsRegExp() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Value::IsRegExp()")) return false;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   return obj->IsJSRegExp();
 }
@@ -2282,16 +2575,14 @@
     str = obj;
   } else {
     i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToString()")) {
-      return Local<String>();
-    }
     LOG_API(isolate, "ToString");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    str = i::Execution::ToString(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToString(
+        isolate, obj).ToHandle(&str);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<String>());
   }
-  return Local<String>(ToApi<String>(str));
+  return ToApiHandle<String>(str);
 }
 
 
@@ -2302,16 +2593,14 @@
     str = obj;
   } else {
     i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToDetailString()")) {
-      return Local<String>();
-    }
     LOG_API(isolate, "ToDetailString");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    str = i::Execution::ToDetailString(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToDetailString(
+        isolate, obj).ToHandle(&str);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<String>());
   }
-  return Local<String>(ToApi<String>(str));
+  return ToApiHandle<String>(str);
 }
 
 
@@ -2322,32 +2611,28 @@
     val = obj;
   } else {
     i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToObject()")) {
-      return Local<v8::Object>();
-    }
     LOG_API(isolate, "ToObject");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    val = i::Execution::ToObject(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToObject(
+        isolate, obj).ToHandle(&val);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Object>());
   }
-  return Local<v8::Object>(ToApi<Object>(val));
+  return ToApiHandle<Object>(val);
 }
 
 
 Local<Boolean> Value::ToBoolean() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsBoolean()) {
-    return Local<Boolean>(ToApi<Boolean>(obj));
+    return ToApiHandle<Boolean>(obj);
   } else {
     i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToBoolean()")) {
-      return Local<Boolean>();
-    }
     LOG_API(isolate, "ToBoolean");
     ENTER_V8(isolate);
-    i::Handle<i::Object> val = i::Execution::ToBoolean(obj);
-    return Local<Boolean>(ToApi<Boolean>(val));
+    i::Handle<i::Object> val =
+        isolate->factory()->ToBoolean(obj->BooleanValue());
+    return ToApiHandle<Boolean>(val);
   }
 }
 
@@ -2358,17 +2643,15 @@
   if (obj->IsNumber()) {
     num = obj;
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToNumber()")) {
-      return Local<Number>();
-    }
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "ToNumber");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    num = i::Execution::ToNumber(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToNumber(
+        isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<Number>());
   }
-  return Local<Number>(ToApi<Number>(num));
+  return ToApiHandle<Number>(num);
 }
 
 
@@ -2378,142 +2661,226 @@
   if (obj->IsSmi()) {
     num = obj;
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToInteger()")) return Local<Integer>();
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "ToInteger");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    num = i::Execution::ToInteger(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToInteger(
+        isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<Integer>());
   }
-  return Local<Integer>(ToApi<Integer>(num));
+  return ToApiHandle<Integer>(num);
+}
+
+
+void i::Internals::CheckInitializedImpl(v8::Isolate* external_isolate) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(external_isolate);
+  Utils::ApiCheck(isolate != NULL &&
+                  isolate->IsInitialized() &&
+                  !isolate->IsDead(),
+                  "v8::internal::Internals::CheckInitialized()",
+                  "Isolate is not initialized or V8 has died");
 }
 
 
 void External::CheckCast(v8::Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::External::Cast()")) return;
-  i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsForeign(),
-           "v8::External::Cast()",
-           "Could not convert to external");
+  Utils::ApiCheck(Utils::OpenHandle(that)->IsExternal(),
+                  "v8::External::Cast()",
+                  "Could not convert to external");
 }
 
 
 void v8::Object::CheckCast(Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Object::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsJSObject(),
-           "v8::Object::Cast()",
-           "Could not convert to object");
+  Utils::ApiCheck(obj->IsJSObject(),
+                  "v8::Object::Cast()",
+                  "Could not convert to object");
 }
 
 
 void v8::Function::CheckCast(Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Function::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsJSFunction(),
-           "v8::Function::Cast()",
-           "Could not convert to function");
+  Utils::ApiCheck(obj->IsJSFunction(),
+                  "v8::Function::Cast()",
+                  "Could not convert to function");
+}
+
+
+void v8::Name::CheckCast(v8::Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  Utils::ApiCheck(obj->IsName(),
+                  "v8::Name::Cast()",
+                  "Could not convert to name");
 }
 
 
 void v8::String::CheckCast(v8::Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::String::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsString(),
-           "v8::String::Cast()",
-           "Could not convert to string");
+  Utils::ApiCheck(obj->IsString(),
+                  "v8::String::Cast()",
+                  "Could not convert to string");
+}
+
+
+void v8::Symbol::CheckCast(v8::Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  Utils::ApiCheck(obj->IsSymbol(),
+                  "v8::Symbol::Cast()",
+                  "Could not convert to symbol");
 }
 
 
 void v8::Number::CheckCast(v8::Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Number::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsNumber(),
-           "v8::Number::Cast()",
-           "Could not convert to number");
+  Utils::ApiCheck(obj->IsNumber(),
+                  "v8::Number::Cast()",
+                  "Could not convert to number");
 }
 
 
 void v8::Integer::CheckCast(v8::Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Integer::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsNumber(),
-           "v8::Integer::Cast()",
-           "Could not convert to number");
+  Utils::ApiCheck(obj->IsNumber(),
+                  "v8::Integer::Cast()",
+                  "Could not convert to number");
 }
 
 
 void v8::Array::CheckCast(Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Array::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsJSArray(),
-           "v8::Array::Cast()",
-           "Could not convert to array");
+  Utils::ApiCheck(obj->IsJSArray(),
+                  "v8::Array::Cast()",
+                  "Could not convert to array");
+}
+
+
+void v8::Promise::CheckCast(Value* that) {
+  Utils::ApiCheck(that->IsPromise(),
+                  "v8::Promise::Cast()",
+                  "Could not convert to promise");
+}
+
+
+void v8::Promise::Resolver::CheckCast(Value* that) {
+  Utils::ApiCheck(that->IsPromise(),
+                  "v8::Promise::Resolver::Cast()",
+                  "Could not convert to promise resolver");
+}
+
+
+void v8::ArrayBuffer::CheckCast(Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  Utils::ApiCheck(obj->IsJSArrayBuffer(),
+                  "v8::ArrayBuffer::Cast()",
+                  "Could not convert to ArrayBuffer");
+}
+
+
+void v8::ArrayBufferView::CheckCast(Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  Utils::ApiCheck(obj->IsJSArrayBufferView(),
+                  "v8::ArrayBufferView::Cast()",
+                  "Could not convert to ArrayBufferView");
+}
+
+
+void v8::TypedArray::CheckCast(Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  Utils::ApiCheck(obj->IsJSTypedArray(),
+                  "v8::TypedArray::Cast()",
+                  "Could not convert to TypedArray");
+}
+
+
+#define CHECK_TYPED_ARRAY_CAST(Type, typeName, TYPE, ctype, size)             \
+  void v8::Type##Array::CheckCast(Value* that) {                              \
+    i::Handle<i::Object> obj = Utils::OpenHandle(that);                       \
+    Utils::ApiCheck(obj->IsJSTypedArray() &&                                  \
+                    i::JSTypedArray::cast(*obj)->type() ==                    \
+                        kExternal##Type##Array,                               \
+                    "v8::" #Type "Array::Cast()",                             \
+                    "Could not convert to " #Type "Array");                   \
+  }
+
+
+TYPED_ARRAYS(CHECK_TYPED_ARRAY_CAST)
+
+#undef CHECK_TYPED_ARRAY_CAST
+
+
+void v8::DataView::CheckCast(Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  Utils::ApiCheck(obj->IsJSDataView(),
+                  "v8::DataView::Cast()",
+                  "Could not convert to DataView");
 }
 
 
 void v8::Date::CheckCast(v8::Value* that) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Date::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->HasSpecificClassOf(isolate->heap()->Date_symbol()),
-           "v8::Date::Cast()",
-           "Could not convert to date");
+  i::Isolate* isolate = NULL;
+  if (obj->IsHeapObject()) isolate = i::HeapObject::cast(*obj)->GetIsolate();
+  Utils::ApiCheck(isolate != NULL &&
+                  obj->HasSpecificClassOf(isolate->heap()->Date_string()),
+                  "v8::Date::Cast()",
+                  "Could not convert to date");
 }
 
 
 void v8::StringObject::CheckCast(v8::Value* that) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::StringObject::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->HasSpecificClassOf(isolate->heap()->String_symbol()),
-           "v8::StringObject::Cast()",
-           "Could not convert to StringObject");
+  i::Isolate* isolate = NULL;
+  if (obj->IsHeapObject()) isolate = i::HeapObject::cast(*obj)->GetIsolate();
+  Utils::ApiCheck(isolate != NULL &&
+                  obj->HasSpecificClassOf(isolate->heap()->String_string()),
+                  "v8::StringObject::Cast()",
+                  "Could not convert to StringObject");
+}
+
+
+void v8::SymbolObject::CheckCast(v8::Value* that) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(that);
+  i::Isolate* isolate = NULL;
+  if (obj->IsHeapObject()) isolate = i::HeapObject::cast(*obj)->GetIsolate();
+  Utils::ApiCheck(isolate != NULL &&
+                  obj->HasSpecificClassOf(isolate->heap()->Symbol_string()),
+                  "v8::SymbolObject::Cast()",
+                  "Could not convert to SymbolObject");
 }
 
 
 void v8::NumberObject::CheckCast(v8::Value* that) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::NumberObject::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->HasSpecificClassOf(isolate->heap()->Number_symbol()),
-           "v8::NumberObject::Cast()",
-           "Could not convert to NumberObject");
+  i::Isolate* isolate = NULL;
+  if (obj->IsHeapObject()) isolate = i::HeapObject::cast(*obj)->GetIsolate();
+  Utils::ApiCheck(isolate != NULL &&
+                  obj->HasSpecificClassOf(isolate->heap()->Number_string()),
+                  "v8::NumberObject::Cast()",
+                  "Could not convert to NumberObject");
 }
 
 
 void v8::BooleanObject::CheckCast(v8::Value* that) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::BooleanObject::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->HasSpecificClassOf(isolate->heap()->Boolean_symbol()),
-           "v8::BooleanObject::Cast()",
-           "Could not convert to BooleanObject");
+  i::Isolate* isolate = NULL;
+  if (obj->IsHeapObject()) isolate = i::HeapObject::cast(*obj)->GetIsolate();
+  Utils::ApiCheck(isolate != NULL &&
+                  obj->HasSpecificClassOf(isolate->heap()->Boolean_string()),
+                  "v8::BooleanObject::Cast()",
+                  "Could not convert to BooleanObject");
 }
 
 
 void v8::RegExp::CheckCast(v8::Value* that) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::RegExp::Cast()")) return;
   i::Handle<i::Object> obj = Utils::OpenHandle(that);
-  ApiCheck(obj->IsJSRegExp(),
-           "v8::RegExp::Cast()",
-           "Could not convert to regular expression");
+  Utils::ApiCheck(obj->IsJSRegExp(),
+                  "v8::RegExp::Cast()",
+                  "Could not convert to regular expression");
 }
 
 
 bool Value::BooleanValue() const {
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  if (obj->IsBoolean()) {
-    return obj->IsTrue();
-  } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::BooleanValue()")) return false;
-    LOG_API(isolate, "BooleanValue");
-    ENTER_V8(isolate);
-    i::Handle<i::Object> value = i::Execution::ToBoolean(obj);
-    return value->IsTrue();
-  }
+  return Utils::OpenHandle(this)->BooleanValue();
 }
 
 
@@ -2523,15 +2890,13 @@
   if (obj->IsNumber()) {
     num = obj;
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::NumberValue()")) {
-      return i::OS::nan_value();
-    }
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "NumberValue");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    num = i::Execution::ToNumber(obj, &has_pending_exception);
-    EXCEPTION_BAILOUT_CHECK(isolate, i::OS::nan_value());
+    has_pending_exception = !i::Execution::ToNumber(
+        isolate, obj).ToHandle(&num);
+    EXCEPTION_BAILOUT_CHECK(isolate, base::OS::nan_value());
   }
   return num->Number();
 }
@@ -2543,12 +2908,12 @@
   if (obj->IsNumber()) {
     num = obj;
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::IntegerValue()")) return 0;
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "IntegerValue");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    num = i::Execution::ToInteger(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToInteger(
+        isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, 0);
   }
   if (num->IsSmi()) {
@@ -2565,15 +2930,14 @@
   if (obj->IsSmi()) {
     num = obj;
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToInt32()")) return Local<Int32>();
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "ToInt32");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    num = i::Execution::ToInt32(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToInt32(isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<Int32>());
   }
-  return Local<Int32>(ToApi<Int32>(num));
+  return ToApiHandle<Int32>(num);
 }
 
 
@@ -2583,15 +2947,15 @@
   if (obj->IsSmi()) {
     num = obj;
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::ToUint32()")) return Local<Uint32>();
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "ToUInt32");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    num = i::Execution::ToUint32(obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToUint32(
+        isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<Uint32>());
   }
-  return Local<Uint32>(ToApi<Uint32>(num));
+  return ToApiHandle<Uint32>(num);
 }
 
 
@@ -2601,20 +2965,20 @@
     if (i::Smi::cast(*obj)->value() >= 0) return Utils::Uint32ToLocal(obj);
     return Local<Uint32>();
   }
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::ToArrayIndex()")) return Local<Uint32>();
+  i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
   LOG_API(isolate, "ToArrayIndex");
   ENTER_V8(isolate);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> string_obj =
-      i::Execution::ToString(obj, &has_pending_exception);
+  i::Handle<i::Object> string_obj;
+  has_pending_exception = !i::Execution::ToString(
+      isolate, obj).ToHandle(&string_obj);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Uint32>());
   i::Handle<i::String> str = i::Handle<i::String>::cast(string_obj);
   uint32_t index;
   if (str->AsArrayIndex(&index)) {
     i::Handle<i::Object> value;
     if (index <= static_cast<uint32_t>(i::Smi::kMaxValue)) {
-      value = i::Handle<i::Object>(i::Smi::FromInt(index));
+      value = i::Handle<i::Object>(i::Smi::FromInt(index), isolate);
     } else {
       value = isolate->factory()->NewNumber(index);
     }
@@ -2629,13 +2993,12 @@
   if (obj->IsSmi()) {
     return i::Smi::cast(*obj)->value();
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::Int32Value()")) return 0;
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "Int32Value (slow)");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> num =
-        i::Execution::ToInt32(obj, &has_pending_exception);
+    i::Handle<i::Object> num;
+    has_pending_exception = !i::Execution::ToInt32(isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, 0);
     if (num->IsSmi()) {
       return i::Smi::cast(*num)->value();
@@ -2648,14 +3011,14 @@
 
 bool Value::Equals(Handle<Value> that) const {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::Equals()")
-      || EmptyCheck("v8::Value::Equals()", this)
-      || EmptyCheck("v8::Value::Equals()", that)) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this, true);
+  if (!Utils::ApiCheck(!obj.is_null() && !that.IsEmpty(),
+                       "v8::Value::Equals()",
+                       "Reading from empty handle")) {
     return false;
   }
   LOG_API(isolate, "Equals");
   ENTER_V8(isolate);
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
   i::Handle<i::Object> other = Utils::OpenHandle(*that);
   // If both obj and other are JSObjects, we'd better compare by identity
   // immediately when going into JS builtin.  The reason is Invoke
@@ -2665,9 +3028,9 @@
   }
   i::Handle<i::Object> args[] = { other };
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> result =
-      CallV8HeapFunction("EQUALS", obj, ARRAY_SIZE(args), args,
-                         &has_pending_exception);
+  i::Handle<i::Object> result;
+  has_pending_exception = !CallV8HeapFunction(
+      "EQUALS", obj, arraysize(args), args).ToHandle(&result);
   EXCEPTION_BAILOUT_CHECK(isolate, false);
   return *result == i::Smi::FromInt(i::EQUAL);
 }
@@ -2675,13 +3038,13 @@
 
 bool Value::StrictEquals(Handle<Value> that) const {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Value::StrictEquals()")
-      || EmptyCheck("v8::Value::StrictEquals()", this)
-      || EmptyCheck("v8::Value::StrictEquals()", that)) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this, true);
+  if (!Utils::ApiCheck(!obj.is_null() && !that.IsEmpty(),
+                       "v8::Value::StrictEquals()",
+                       "Reading from empty handle")) {
     return false;
   }
   LOG_API(isolate, "StrictEquals");
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
   i::Handle<i::Object> other = Utils::OpenHandle(*that);
   // Must check HeapNumber first, since NaN !== NaN.
   if (obj->IsHeapNumber()) {
@@ -2689,14 +3052,15 @@
     double x = obj->Number();
     double y = other->Number();
     // Must check explicitly for NaN:s on Windows, but -0 works fine.
-    return x == y && !isnan(x) && !isnan(y);
+    return x == y && !std::isnan(x) && !std::isnan(y);
   } else if (*obj == *other) {  // Also covers Booleans.
     return true;
   } else if (obj->IsSmi()) {
     return other->IsNumber() && obj->Number() == other->Number();
   } else if (obj->IsString()) {
     return other->IsString() &&
-      i::String::cast(*obj)->Equals(i::String::cast(*other));
+        i::String::Equals(i::Handle<i::String>::cast(obj),
+                          i::Handle<i::String>::cast(other));
   } else if (obj->IsUndefined() || obj->IsUndetectableObject()) {
     return other->IsUndefined() || other->IsUndetectableObject();
   } else {
@@ -2705,18 +3069,30 @@
 }
 
 
+bool Value::SameValue(Handle<Value> that) const {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this, true);
+  if (!Utils::ApiCheck(!obj.is_null() && !that.IsEmpty(),
+                       "v8::Value::SameValue()",
+                       "Reading from empty handle")) {
+    return false;
+  }
+  i::Handle<i::Object> other = Utils::OpenHandle(*that);
+  return obj->SameValue(*other);
+}
+
+
 uint32_t Value::Uint32Value() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsSmi()) {
     return i::Smi::cast(*obj)->value();
   } else {
-    i::Isolate* isolate = i::Isolate::Current();
-    if (IsDeadCheck(isolate, "v8::Value::Uint32Value()")) return 0;
+    i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
     LOG_API(isolate, "Uint32Value");
     ENTER_V8(isolate);
     EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> num =
-        i::Execution::ToUint32(obj, &has_pending_exception);
+    i::Handle<i::Object> num;
+    has_pending_exception = !i::Execution::ToUint32(
+        isolate, obj).ToHandle(&num);
     EXCEPTION_BAILOUT_CHECK(isolate, 0);
     if (num->IsSmi()) {
       return i::Smi::cast(*num)->value();
@@ -2727,8 +3103,7 @@
 }
 
 
-bool v8::Object::Set(v8::Handle<Value> key, v8::Handle<Value> value,
-                     v8::PropertyAttribute attribs) {
+bool v8::Object::Set(v8::Handle<Value> key, v8::Handle<Value> value) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::Set()", return false);
   ENTER_V8(isolate);
@@ -2737,13 +3112,9 @@
   i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
   i::Handle<i::Object> value_obj = Utils::OpenHandle(*value);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj = i::SetProperty(
-      self,
-      key_obj,
-      value_obj,
-      static_cast<PropertyAttributes>(attribs),
-      i::kNonStrictMode);
-  has_pending_exception = obj.is_null();
+  has_pending_exception =
+      i::Runtime::SetObjectProperty(isolate, self, key_obj, value_obj,
+                                    i::SLOPPY).is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, false);
   return true;
 }
@@ -2757,13 +3128,8 @@
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   i::Handle<i::Object> value_obj = Utils::OpenHandle(*value);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj = i::JSObject::SetElement(
-      self,
-      index,
-      value_obj,
-      NONE,
-      i::kNonStrictMode);
-  has_pending_exception = obj.is_null();
+  has_pending_exception = i::JSObject::SetElement(
+      self, index, value_obj, NONE, i::SLOPPY).is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, false);
   return true;
 }
@@ -2780,17 +3146,22 @@
   i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
   i::Handle<i::Object> value_obj = Utils::OpenHandle(*value);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj = i::ForceSetProperty(
+  has_pending_exception = i::Runtime::DefineObjectProperty(
       self,
       key_obj,
       value_obj,
-      static_cast<PropertyAttributes>(attribs));
-  has_pending_exception = obj.is_null();
+      static_cast<PropertyAttributes>(attribs)).is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, false);
   return true;
 }
 
 
+bool v8::Object::SetPrivate(v8::Handle<Private> key, v8::Handle<Value> value) {
+  return ForceSet(v8::Handle<Value>(reinterpret_cast<Value*>(*key)),
+                  value, DontEnum);
+}
+
+
 bool v8::Object::ForceDelete(v8::Handle<Value> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::ForceDelete()", return false);
@@ -2799,13 +3170,18 @@
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
 
-  // When turning on access checks for a global object deoptimize all functions
-  // as optimized code does not always handle access checks.
-  i::Deoptimizer::DeoptimizeGlobalObject(*self);
+  // When deleting a property on the global object using ForceDelete
+  // deoptimize all functions as optimized code does not check for the hole
+  // value with DontDelete properties.  We have to deoptimize all contexts
+  // because of possible cross-context inlined functions.
+  if (self->IsJSGlobalProxy() || self->IsGlobalObject()) {
+    i::Deoptimizer::DeoptimizeAll(isolate);
+  }
 
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj = i::ForceDeleteProperty(self, key_obj);
-  has_pending_exception = obj.is_null();
+  i::Handle<i::Object> obj;
+  has_pending_exception = !i::Runtime::DeleteObjectProperty(
+      isolate, self, key_obj, i::JSReceiver::FORCE_DELETION).ToHandle(&obj);
   EXCEPTION_BAILOUT_CHECK(isolate, false);
   return obj->IsTrue();
 }
@@ -2818,8 +3194,9 @@
   i::Handle<i::Object> self = Utils::OpenHandle(this);
   i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> result = i::GetProperty(self, key_obj);
-  has_pending_exception = result.is_null();
+  i::Handle<i::Object> result;
+  has_pending_exception =
+      !i::Runtime::GetObjectProperty(isolate, self, key_obj).ToHandle(&result);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
   return Utils::ToLocal(result);
 }
@@ -2831,41 +3208,71 @@
   ENTER_V8(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> result = i::Object::GetElement(self, index);
-  has_pending_exception = result.is_null();
+  i::Handle<i::Object> result;
+  has_pending_exception =
+      !i::Object::GetElement(isolate, self, index).ToHandle(&result);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
   return Utils::ToLocal(result);
 }
 
 
+Local<Value> v8::Object::GetPrivate(v8::Handle<Private> key) {
+  return Get(v8::Handle<Value>(reinterpret_cast<Value*>(*key)));
+}
+
+
 PropertyAttribute v8::Object::GetPropertyAttributes(v8::Handle<Value> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  ON_BAILOUT(isolate, "v8::Object::GetPropertyAttribute()",
+  ON_BAILOUT(isolate, "v8::Object::GetPropertyAttributes()",
              return static_cast<PropertyAttribute>(NONE));
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
-  if (!key_obj->IsString()) {
+  if (!key_obj->IsName()) {
     EXCEPTION_PREAMBLE(isolate);
-    key_obj = i::Execution::ToString(key_obj, &has_pending_exception);
+    has_pending_exception = !i::Execution::ToString(
+        isolate, key_obj).ToHandle(&key_obj);
     EXCEPTION_BAILOUT_CHECK(isolate, static_cast<PropertyAttribute>(NONE));
   }
-  i::Handle<i::String> key_string = i::Handle<i::String>::cast(key_obj);
-  PropertyAttributes result = self->GetPropertyAttribute(*key_string);
-  if (result == ABSENT) return static_cast<PropertyAttribute>(NONE);
-  return static_cast<PropertyAttribute>(result);
+  i::Handle<i::Name> key_name = i::Handle<i::Name>::cast(key_obj);
+  EXCEPTION_PREAMBLE(isolate);
+  Maybe<PropertyAttributes> result =
+      i::JSReceiver::GetPropertyAttributes(self, key_name);
+  has_pending_exception = !result.has_value;
+  EXCEPTION_BAILOUT_CHECK(isolate, static_cast<PropertyAttribute>(NONE));
+  if (result.value == ABSENT) return static_cast<PropertyAttribute>(NONE);
+  return static_cast<PropertyAttribute>(result.value);
+}
+
+
+Local<Value> v8::Object::GetOwnPropertyDescriptor(Local<String> key) {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ON_BAILOUT(isolate, "v8::Object::GetOwnPropertyDescriptor()",
+             return Local<Value>());
+  ENTER_V8(isolate);
+  i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
+  i::Handle<i::Name> key_name = Utils::OpenHandle(*key);
+  i::Handle<i::Object> args[] = { obj, key_name };
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> result;
+  has_pending_exception = !CallV8HeapFunction(
+      "ObjectGetOwnPropertyDescriptor",
+      isolate->factory()->undefined_value(),
+      arraysize(args),
+      args).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
+  return Utils::ToLocal(result);
 }
 
 
 Local<Value> v8::Object::GetPrototype() {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  ON_BAILOUT(isolate, "v8::Object::GetPrototype()",
-             return Local<v8::Value>());
+  ON_BAILOUT(isolate, "v8::Object::GetPrototype()", return Local<v8::Value>());
   ENTER_V8(isolate);
   i::Handle<i::Object> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> result(self->GetPrototype());
-  return Utils::ToLocal(result);
+  i::PrototypeIterator iter(isolate, self);
+  return Utils::ToLocal(i::PrototypeIterator::GetCurrent(iter));
 }
 
 
@@ -2879,7 +3286,8 @@
   // to propagate outside.
   TryCatch try_catch;
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> result = i::SetPrototype(self, value_obj);
+  i::MaybeHandle<i::Object> result =
+      i::JSObject::SetPrototype(self, value_obj, false);
   has_pending_exception = result.is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, false);
   return true;
@@ -2893,14 +3301,17 @@
              "v8::Object::FindInstanceInPrototypeChain()",
              return Local<v8::Object>());
   ENTER_V8(isolate);
-  i::JSObject* object = *Utils::OpenHandle(this);
+  i::PrototypeIterator iter(isolate, *Utils::OpenHandle(this),
+                            i::PrototypeIterator::START_AT_RECEIVER);
   i::FunctionTemplateInfo* tmpl_info = *Utils::OpenHandle(*tmpl);
-  while (!object->IsInstanceOf(tmpl_info)) {
-    i::Object* prototype = object->GetPrototype();
-    if (!prototype->IsJSObject()) return Local<Object>();
-    object = i::JSObject::cast(prototype);
+  while (!tmpl_info->IsTemplateFor(iter.GetCurrent())) {
+    iter.Advance();
+    if (iter.IsAtEnd()) {
+      return Local<Object>();
+    }
   }
-  return Utils::ToLocal(i::Handle<i::JSObject>(object));
+  return Utils::ToLocal(
+      i::handle(i::JSObject::cast(iter.GetCurrent()), isolate));
 }
 
 
@@ -2911,10 +3322,11 @@
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  bool threw = false;
-  i::Handle<i::FixedArray> value =
-      i::GetKeysInFixedArrayFor(self, i::INCLUDE_PROTOS, &threw);
-  if (threw) return Local<v8::Array>();
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::FixedArray> value;
+  has_pending_exception = !i::JSReceiver::GetKeys(
+      self, i::JSReceiver::INCLUDE_PROTOS).ToHandle(&value);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Array>());
   // Because we use caching to speed up enumeration it is important
   // to never change the result of the basic enumeration function so
   // we clone the result.
@@ -2932,10 +3344,11 @@
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  bool threw = false;
-  i::Handle<i::FixedArray> value =
-      i::GetKeysInFixedArrayFor(self, i::LOCAL_ONLY, &threw);
-  if (threw) return Local<v8::Array>();
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::FixedArray> value;
+  has_pending_exception = !i::JSReceiver::GetKeys(
+      self, i::JSReceiver::OWN_ONLY).ToHandle(&value);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Array>());
   // Because we use caching to speed up enumeration it is important
   // to never change the result of the basic enumeration function so
   // we clone the result.
@@ -2947,34 +3360,34 @@
 
 
 Local<String> v8::Object::ObjectProtoToString() {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  ON_BAILOUT(isolate, "v8::Object::ObjectProtoToString()",
+  i::Isolate* i_isolate = Utils::OpenHandle(this)->GetIsolate();
+  Isolate* isolate = reinterpret_cast<Isolate*>(i_isolate);
+  ON_BAILOUT(i_isolate, "v8::Object::ObjectProtoToString()",
              return Local<v8::String>());
-  ENTER_V8(isolate);
+  ENTER_V8(i_isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
 
-  i::Handle<i::Object> name(self->class_name());
+  i::Handle<i::Object> name(self->class_name(), i_isolate);
 
   // Native implementation of Object.prototype.toString (v8natives.js):
-  //   var c = %ClassOf(this);
+  //   var c = %_ClassOf(this);
   //   if (c === 'Arguments') c  = 'Object';
   //   return "[object " + c + "]";
 
   if (!name->IsString()) {
-    return v8::String::New("[object ]");
-
+    return v8::String::NewFromUtf8(isolate, "[object ]");
   } else {
     i::Handle<i::String> class_name = i::Handle<i::String>::cast(name);
-    if (class_name->IsEqualTo(i::CStrVector("Arguments"))) {
-      return v8::String::New("[object Object]");
-
+    if (i::String::Equals(class_name,
+                          i_isolate->factory()->Arguments_string())) {
+      return v8::String::NewFromUtf8(isolate, "[object Object]");
     } else {
       const char* prefix = "[object ";
       Local<String> str = Utils::ToLocal(class_name);
       const char* postfix = "]";
 
       int prefix_len = i::StrLength(prefix);
-      int str_len = str->Length();
+      int str_len = str->Utf8Length();
       int postfix_len = i::StrLength(postfix);
 
       int buf_len = prefix_len + str_len + postfix_len;
@@ -2982,18 +3395,19 @@
 
       // Write prefix.
       char* ptr = buf.start();
-      memcpy(ptr, prefix, prefix_len * v8::internal::kCharSize);
+      i::MemCopy(ptr, prefix, prefix_len * v8::internal::kCharSize);
       ptr += prefix_len;
 
       // Write real content.
-      str->WriteAscii(ptr, 0, str_len);
+      str->WriteUtf8(ptr, str_len);
       ptr += str_len;
 
       // Write postfix.
-      memcpy(ptr, postfix, postfix_len * v8::internal::kCharSize);
+      i::MemCopy(ptr, postfix, postfix_len * v8::internal::kCharSize);
 
       // Copy the buffer into a heap-allocated string and return it.
-      Local<String> result = v8::String::New(buf.start(), buf_len);
+      Local<String> result = v8::String::NewFromUtf8(
+          isolate, buf.start(), String::kNormalString, buf_len);
       return result;
     }
   }
@@ -3011,24 +3425,46 @@
 }
 
 
-bool v8::Object::Delete(v8::Handle<String> key) {
+bool v8::Object::Delete(v8::Handle<Value> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::Delete()", return false);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
-  return i::JSObject::DeleteProperty(self, key_obj)->IsTrue();
+  i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> obj;
+  has_pending_exception = !i::Runtime::DeleteObjectProperty(
+      isolate, self, key_obj, i::JSReceiver::NORMAL_DELETION).ToHandle(&obj);
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return obj->IsTrue();
 }
 
 
-bool v8::Object::Has(v8::Handle<String> key) {
+bool v8::Object::DeletePrivate(v8::Handle<Private> key) {
+  return Delete(v8::Handle<Value>(reinterpret_cast<Value*>(*key)));
+}
+
+
+bool v8::Object::Has(v8::Handle<Value> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::Has()", return false);
   ENTER_V8(isolate);
-  i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
-  return self->HasProperty(*key_obj);
+  i::Handle<i::JSReceiver> self = Utils::OpenHandle(this);
+  i::Handle<i::Object> key_obj = Utils::OpenHandle(*key);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> obj;
+  has_pending_exception = !i::Runtime::HasObjectProperty(
+      isolate, self, key_obj).ToHandle(&obj);
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return obj->IsTrue();
+}
+
+
+bool v8::Object::HasPrivate(v8::Handle<Private> key) {
+  // TODO(rossberg): this should use HasOwnProperty, but we'd need to
+  // generalise that to a (noy yet existant) Name argument first.
+  return Has(v8::Handle<Value>(reinterpret_cast<Value*>(*key)));
 }
 
 
@@ -3037,9 +3473,15 @@
   ON_BAILOUT(isolate, "v8::Object::DeleteProperty()",
              return false);
   ENTER_V8(isolate);
-  HandleScope scope;
+  HandleScope scope(reinterpret_cast<Isolate*>(isolate));
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  return i::JSObject::DeleteElement(self, index)->IsTrue();
+
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> obj;
+  has_pending_exception =
+      !i::JSReceiver::DeleteElement(self, index).ToHandle(&obj);
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return obj->IsTrue();
 }
 
 
@@ -3047,28 +3489,93 @@
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::HasProperty()", return false);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  return self->HasElement(index);
+  EXCEPTION_PREAMBLE(isolate);
+  Maybe<bool> maybe = i::JSReceiver::HasElement(self, index);
+  has_pending_exception = !maybe.has_value;
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return maybe.value;
+}
+
+
+template<typename Getter, typename Setter, typename Data>
+static inline bool ObjectSetAccessor(Object* obj,
+                                     Handle<Name> name,
+                                     Getter getter,
+                                     Setter setter,
+                                     Data data,
+                                     AccessControl settings,
+                                     PropertyAttribute attributes) {
+  i::Isolate* isolate = Utils::OpenHandle(obj)->GetIsolate();
+  ON_BAILOUT(isolate, "v8::Object::SetAccessor()", return false);
+  ENTER_V8(isolate);
+  i::HandleScope scope(isolate);
+  v8::Handle<AccessorSignature> signature;
+  i::Handle<i::AccessorInfo> info = MakeAccessorInfo(
+      name, getter, setter, data, settings, attributes, signature);
+  if (info.is_null()) return false;
+  bool fast = Utils::OpenHandle(obj)->HasFastProperties();
+  i::Handle<i::Object> result;
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+      isolate, result,
+      i::JSObject::SetAccessor(Utils::OpenHandle(obj), info),
+      false);
+  if (result->IsUndefined()) return false;
+  if (fast) i::JSObject::MigrateSlowToFast(Utils::OpenHandle(obj), 0);
+  return true;
 }
 
 
 bool Object::SetAccessor(Handle<String> name,
-                         AccessorGetter getter,
-                         AccessorSetter setter,
+                         AccessorGetterCallback getter,
+                         AccessorSetterCallback setter,
                          v8::Handle<Value> data,
                          AccessControl settings,
                          PropertyAttribute attributes) {
+  return ObjectSetAccessor(
+      this, name, getter, setter, data, settings, attributes);
+}
+
+
+bool Object::SetAccessor(Handle<Name> name,
+                         AccessorNameGetterCallback getter,
+                         AccessorNameSetterCallback setter,
+                         v8::Handle<Value> data,
+                         AccessControl settings,
+                         PropertyAttribute attributes) {
+  return ObjectSetAccessor(
+      this, name, getter, setter, data, settings, attributes);
+}
+
+
+bool Object::SetDeclaredAccessor(Local<Name> name,
+                                 Local<DeclaredAccessorDescriptor> descriptor,
+                                 PropertyAttribute attributes,
+                                 AccessControl settings) {
+  void* null = NULL;
+  return ObjectSetAccessor(
+      this, name, descriptor, null, null, settings, attributes);
+}
+
+
+void Object::SetAccessorProperty(Local<Name> name,
+                                 Local<Function> getter,
+                                 Handle<Function> setter,
+                                 PropertyAttribute attribute,
+                                 AccessControl settings) {
+  // TODO(verwaest): Remove |settings|.
+  DCHECK_EQ(v8::DEFAULT, settings);
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  ON_BAILOUT(isolate, "v8::Object::SetAccessor()", return false);
+  ON_BAILOUT(isolate, "v8::Object::SetAccessorProperty()", return);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  i::Handle<i::AccessorInfo> info = MakeAccessorInfo(name,
-                                                     getter, setter, data,
-                                                     settings, attributes);
-  bool fast = Utils::OpenHandle(this)->HasFastProperties();
-  i::Handle<i::Object> result = i::SetAccessor(Utils::OpenHandle(this), info);
-  if (result.is_null() || result->IsUndefined()) return false;
-  if (fast) i::JSObject::TransformToFastProperties(Utils::OpenHandle(this), 0);
-  return true;
+  i::Handle<i::Object> getter_i = v8::Utils::OpenHandle(*getter);
+  i::Handle<i::Object> setter_i = v8::Utils::OpenHandle(*setter, true);
+  if (setter_i.is_null()) setter_i = isolate->factory()->null_value();
+  i::JSObject::DefineAccessor(v8::Utils::OpenHandle(this),
+                              v8::Utils::OpenHandle(*name),
+                              getter_i,
+                              setter_i,
+                              static_cast<PropertyAttributes>(attribute));
 }
 
 
@@ -3076,8 +3583,12 @@
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::HasOwnProperty()",
              return false);
-  return Utils::OpenHandle(this)->HasLocalProperty(
-      *Utils::OpenHandle(*key));
+  EXCEPTION_PREAMBLE(isolate);
+  Maybe<bool> maybe = i::JSReceiver::HasOwnProperty(Utils::OpenHandle(this),
+                                                    Utils::OpenHandle(*key));
+  has_pending_exception = !maybe.has_value;
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return maybe.value;
 }
 
 
@@ -3085,16 +3596,25 @@
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::HasRealNamedProperty()",
              return false);
-  return Utils::OpenHandle(this)->HasRealNamedProperty(
-      *Utils::OpenHandle(*key));
+  EXCEPTION_PREAMBLE(isolate);
+  Maybe<bool> maybe = i::JSObject::HasRealNamedProperty(
+      Utils::OpenHandle(this), Utils::OpenHandle(*key));
+  has_pending_exception = !maybe.has_value;
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return maybe.value;
 }
 
 
 bool v8::Object::HasRealIndexedProperty(uint32_t index) {
-  ON_BAILOUT(Utils::OpenHandle(this)->GetIsolate(),
-             "v8::Object::HasRealIndexedProperty()",
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ON_BAILOUT(isolate, "v8::Object::HasRealIndexedProperty()",
              return false);
-  return Utils::OpenHandle(this)->HasRealElementProperty(index);
+  EXCEPTION_PREAMBLE(isolate);
+  Maybe<bool> maybe =
+      i::JSObject::HasRealElementProperty(Utils::OpenHandle(this), index);
+  has_pending_exception = !maybe.has_value;
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return maybe.value;
 }
 
 
@@ -3104,8 +3624,12 @@
              "v8::Object::HasRealNamedCallbackProperty()",
              return false);
   ENTER_V8(isolate);
-  return Utils::OpenHandle(this)->HasRealNamedCallbackProperty(
-      *Utils::OpenHandle(*key));
+  EXCEPTION_PREAMBLE(isolate);
+  Maybe<bool> maybe = i::JSObject::HasRealNamedCallbackProperty(
+      Utils::OpenHandle(this), Utils::OpenHandle(*key));
+  has_pending_exception = !maybe.has_value;
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return maybe.value;
 }
 
 
@@ -3125,31 +3649,20 @@
 }
 
 
-static Local<Value> GetPropertyByLookup(i::Isolate* isolate,
-                                        i::Handle<i::JSObject> receiver,
-                                        i::Handle<i::String> name,
-                                        i::LookupResult* lookup) {
-  if (!lookup->IsProperty()) {
-    // No real property was found.
-    return Local<Value>();
-  }
+static Local<Value> GetPropertyByLookup(i::LookupIterator* it) {
+  // If the property being looked up is a callback, it can throw an exception.
+  EXCEPTION_PREAMBLE(it->isolate());
+  i::Handle<i::Object> result;
+  has_pending_exception = !i::Object::GetProperty(it).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(it->isolate(), Local<Value>());
 
-  // If the property being looked up is a callback, it can throw
-  // an exception.
-  EXCEPTION_PREAMBLE(isolate);
-  PropertyAttributes ignored;
-  i::Handle<i::Object> result =
-      i::Object::GetProperty(receiver, receiver, lookup, name,
-                             &ignored);
-  has_pending_exception = result.is_null();
-  EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
-
-  return Utils::ToLocal(result);
+  if (it->IsFound()) return Utils::ToLocal(result);
+  return Local<Value>();
 }
 
 
 Local<Value> v8::Object::GetRealNamedPropertyInPrototypeChain(
-      Handle<String> key) {
+    Handle<String> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate,
              "v8::Object::GetRealNamedPropertyInPrototypeChain()",
@@ -3157,9 +3670,12 @@
   ENTER_V8(isolate);
   i::Handle<i::JSObject> self_obj = Utils::OpenHandle(this);
   i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
-  i::LookupResult lookup(isolate);
-  self_obj->LookupRealNamedPropertyInPrototypes(*key_obj, &lookup);
-  return GetPropertyByLookup(isolate, self_obj, key_obj, &lookup);
+  i::PrototypeIterator iter(isolate, self_obj);
+  if (iter.IsAtEnd()) return Local<Value>();
+  i::Handle<i::Object> proto = i::PrototypeIterator::GetCurrent(iter);
+  i::LookupIterator it(self_obj, key_obj, i::Handle<i::JSReceiver>::cast(proto),
+                       i::LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
+  return GetPropertyByLookup(&it);
 }
 
 
@@ -3170,9 +3686,9 @@
   ENTER_V8(isolate);
   i::Handle<i::JSObject> self_obj = Utils::OpenHandle(this);
   i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
-  i::LookupResult lookup(isolate);
-  self_obj->LookupRealNamedProperty(*key_obj, &lookup);
-  return GetPropertyByLookup(isolate, self_obj, key_obj, &lookup);
+  i::LookupIterator it(self_obj, key_obj,
+                       i::LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
+  return GetPropertyByLookup(&it);
 }
 
 
@@ -3190,10 +3706,9 @@
   // as optimized code does not always handle access checks.
   i::Deoptimizer::DeoptimizeGlobalObject(*obj);
 
-  i::Handle<i::Map> new_map =
-      isolate->factory()->CopyMapDropTransitions(i::Handle<i::Map>(obj->map()));
+  i::Handle<i::Map> new_map = i::Map::Copy(i::Handle<i::Map>(obj->map()));
   new_map->set_is_access_check_needed(true);
-  obj->set_map(*new_map);
+  i::JSObject::MigrateToMap(obj, new_map);
 }
 
 
@@ -3208,35 +3723,20 @@
   ENTER_V8(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::JSObject> result = i::Copy(self);
+  i::Handle<i::JSObject> result = isolate->factory()->CopyJSObject(self);
   has_pending_exception = result.is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Object>());
   return Utils::ToLocal(result);
 }
 
 
-static i::Context* GetCreationContext(i::JSObject* object) {
-  i::Object* constructor = object->map()->constructor();
-  i::JSFunction* function;
-  if (!constructor->IsJSFunction()) {
-    // Functions have null as a constructor,
-    // but any JSFunction knows its context immediately.
-    ASSERT(object->IsJSFunction());
-    function = i::JSFunction::cast(object);
-  } else {
-    function = i::JSFunction::cast(constructor);
-  }
-  return function->context()->global_context();
-}
-
-
 Local<v8::Context> v8::Object::CreationContext() {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate,
              "v8::Object::CreationContext()", return Local<v8::Context>());
   ENTER_V8(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Context* context = GetCreationContext(*self);
+  i::Context* context = self->GetCreationContext();
   return Utils::ToLocal(i::Handle<i::Context>(context));
 }
 
@@ -3247,7 +3747,7 @@
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  return i::JSObject::GetIdentityHash(self);
+  return i::JSReceiver::GetOrCreateIdentityHash(self)->value();
 }
 
 
@@ -3255,13 +3755,16 @@
                                 v8::Handle<v8::Value> value) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::SetHiddenValue()", return false);
+  if (value.IsEmpty()) return DeleteHiddenValue(key);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
+  i::Handle<i::String> key_string =
+      isolate->factory()->InternalizeString(key_obj);
   i::Handle<i::Object> value_obj = Utils::OpenHandle(*value);
   i::Handle<i::Object> result =
-      i::JSObject::SetHiddenProperty(self, key_obj, value_obj);
+      i::JSObject::SetHiddenProperty(self, key_string, value_obj);
   return *result == *self;
 }
 
@@ -3273,8 +3776,10 @@
   ENTER_V8(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
-  i::Handle<i::Object> result(self->GetHiddenProperty(*key_obj));
-  if (result->IsUndefined()) return v8::Local<v8::Value>();
+  i::Handle<i::String> key_string =
+      isolate->factory()->InternalizeString(key_obj);
+  i::Handle<i::Object> result(self->GetHiddenProperty(key_string), isolate);
+  if (result->IsTheHole()) return v8::Local<v8::Value>();
   return Utils::ToLocal(result);
 }
 
@@ -3286,7 +3791,9 @@
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
-  self->DeleteHiddenProperty(*key_obj);
+  i::Handle<i::String> key_string =
+      isolate->factory()->InternalizeString(key_obj);
+  i::JSObject::DeleteHiddenProperty(self, key_string);
   return true;
 }
 
@@ -3296,33 +3803,12 @@
 static i::ElementsKind GetElementsKindFromExternalArrayType(
     ExternalArrayType array_type) {
   switch (array_type) {
-    case kExternalByteArray:
-      return i::EXTERNAL_BYTE_ELEMENTS;
-      break;
-    case kExternalUnsignedByteArray:
-      return i::EXTERNAL_UNSIGNED_BYTE_ELEMENTS;
-      break;
-    case kExternalShortArray:
-      return i::EXTERNAL_SHORT_ELEMENTS;
-      break;
-    case kExternalUnsignedShortArray:
-      return i::EXTERNAL_UNSIGNED_SHORT_ELEMENTS;
-      break;
-    case kExternalIntArray:
-      return i::EXTERNAL_INT_ELEMENTS;
-      break;
-    case kExternalUnsignedIntArray:
-      return i::EXTERNAL_UNSIGNED_INT_ELEMENTS;
-      break;
-    case kExternalFloatArray:
-      return i::EXTERNAL_FLOAT_ELEMENTS;
-      break;
-    case kExternalDoubleArray:
-      return i::EXTERNAL_DOUBLE_ELEMENTS;
-      break;
-    case kExternalPixelArray:
-      return i::EXTERNAL_PIXEL_ELEMENTS;
-      break;
+#define ARRAY_TYPE_TO_ELEMENTS_KIND(Type, type, TYPE, ctype, size)            \
+    case kExternal##Type##Array:                                              \
+      return i::EXTERNAL_##TYPE##_ELEMENTS;
+
+    TYPED_ARRAYS(ARRAY_TYPE_TO_ELEMENTS_KIND)
+#undef ARRAY_TYPE_TO_ELEMENTS_KIND
   }
   UNREACHABLE();
   return i::DICTIONARY_ELEMENTS;
@@ -3338,12 +3824,11 @@
       isolate->factory()->NewExternalArray(length, array_type, data);
 
   i::Handle<i::Map> external_array_map =
-      isolate->factory()->GetElementsTransitionMap(
+      i::JSObject::GetElementsTransitionMap(
           object,
           GetElementsKindFromExternalArrayType(array_type));
 
-  object->set_map(*external_array_map);
-  object->set_elements(*array);
+  i::JSObject::SetMapAndElements(object, external_array_map, array);
 }
 
 }  // namespace
@@ -3354,18 +3839,19 @@
   ON_BAILOUT(isolate, "v8::SetElementsToPixelData()", return);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  if (!ApiCheck(length <= i::ExternalPixelArray::kMaxLength,
-                "v8::Object::SetIndexedPropertiesToPixelData()",
-                "length exceeds max acceptable value")) {
+  if (!Utils::ApiCheck(length >= 0 &&
+                       length <= i::ExternalUint8ClampedArray::kMaxLength,
+                       "v8::Object::SetIndexedPropertiesToPixelData()",
+                       "length exceeds max acceptable value")) {
     return;
   }
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  if (!ApiCheck(!self->IsJSArray(),
-                "v8::Object::SetIndexedPropertiesToPixelData()",
-                "JSArray is not supported")) {
+  if (!Utils::ApiCheck(!self->IsJSArray(),
+                       "v8::Object::SetIndexedPropertiesToPixelData()",
+                       "JSArray is not supported")) {
     return;
   }
-  PrepareExternalArrayElements(self, data, kExternalPixelArray, length);
+  PrepareExternalArrayElements(self, data, kExternalUint8ClampedArray, length);
 }
 
 
@@ -3373,7 +3859,7 @@
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   ON_BAILOUT(self->GetIsolate(), "v8::HasIndexedPropertiesInPixelData()",
              return false);
-  return self->HasExternalPixelElements();
+  return self->HasExternalUint8ClampedElements();
 }
 
 
@@ -3381,9 +3867,9 @@
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   ON_BAILOUT(self->GetIsolate(), "v8::GetIndexedPropertiesPixelData()",
              return NULL);
-  if (self->HasExternalPixelElements()) {
-    return i::ExternalPixelArray::cast(self->elements())->
-        external_pixel_pointer();
+  if (self->HasExternalUint8ClampedElements()) {
+    return i::ExternalUint8ClampedArray::cast(self->elements())->
+        external_uint8_clamped_pointer();
   } else {
     return NULL;
   }
@@ -3394,8 +3880,8 @@
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
   ON_BAILOUT(self->GetIsolate(), "v8::GetIndexedPropertiesPixelDataLength()",
              return -1);
-  if (self->HasExternalPixelElements()) {
-    return i::ExternalPixelArray::cast(self->elements())->length();
+  if (self->HasExternalUint8ClampedElements()) {
+    return i::ExternalUint8ClampedArray::cast(self->elements())->length();
   } else {
     return -1;
   }
@@ -3410,15 +3896,15 @@
   ON_BAILOUT(isolate, "v8::SetIndexedPropertiesToExternalArrayData()", return);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
-  if (!ApiCheck(length <= i::ExternalArray::kMaxLength,
-                "v8::Object::SetIndexedPropertiesToExternalArrayData()",
-                "length exceeds max acceptable value")) {
+  if (!Utils::ApiCheck(length >= 0 && length <= i::ExternalArray::kMaxLength,
+                       "v8::Object::SetIndexedPropertiesToExternalArrayData()",
+                       "length exceeds max acceptable value")) {
     return;
   }
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  if (!ApiCheck(!self->IsJSArray(),
-                "v8::Object::SetIndexedPropertiesToExternalArrayData()",
-                "JSArray is not supported")) {
+  if (!Utils::ApiCheck(!self->IsJSArray(),
+                       "v8::Object::SetIndexedPropertiesToExternalArrayData()",
+                       "JSArray is not supported")) {
     return;
   }
   PrepareExternalArrayElements(self, data, array_type, length);
@@ -3453,24 +3939,11 @@
              "v8::GetIndexedPropertiesExternalArrayDataType()",
              return static_cast<ExternalArrayType>(-1));
   switch (self->elements()->map()->instance_type()) {
-    case i::EXTERNAL_BYTE_ARRAY_TYPE:
-      return kExternalByteArray;
-    case i::EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE:
-      return kExternalUnsignedByteArray;
-    case i::EXTERNAL_SHORT_ARRAY_TYPE:
-      return kExternalShortArray;
-    case i::EXTERNAL_UNSIGNED_SHORT_ARRAY_TYPE:
-      return kExternalUnsignedShortArray;
-    case i::EXTERNAL_INT_ARRAY_TYPE:
-      return kExternalIntArray;
-    case i::EXTERNAL_UNSIGNED_INT_ARRAY_TYPE:
-      return kExternalUnsignedIntArray;
-    case i::EXTERNAL_FLOAT_ARRAY_TYPE:
-      return kExternalFloatArray;
-    case i::EXTERNAL_DOUBLE_ARRAY_TYPE:
-      return kExternalDoubleArray;
-    case i::EXTERNAL_PIXEL_ARRAY_TYPE:
-      return kExternalPixelArray;
+#define INSTANCE_TYPE_TO_ARRAY_TYPE(Type, type, TYPE, ctype, size)            \
+    case i::EXTERNAL_##TYPE##_ARRAY_TYPE:                                     \
+      return kExternal##Type##Array;
+    TYPED_ARRAYS(INSTANCE_TYPE_TO_ARRAY_TYPE)
+#undef INSTANCE_TYPE_TO_ARRAY_TYPE
     default:
       return static_cast<ExternalArrayType>(-1);
   }
@@ -3496,12 +3969,11 @@
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
-  if (obj->IsJSFunction()) return true;
-  return i::Execution::GetFunctionDelegate(obj)->IsJSFunction();
+  return obj->IsCallable();
 }
 
 
-Local<v8::Value> Object::CallAsFunction(v8::Handle<v8::Object> recv,
+Local<v8::Value> Object::CallAsFunction(v8::Handle<v8::Value> recv,
                                         int argc,
                                         v8::Handle<v8::Value> argv[]) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
@@ -3509,6 +3981,7 @@
              return Local<v8::Value>());
   LOG_API(isolate, "Object::CallAsFunction");
   ENTER_V8(isolate);
+  i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
   i::Handle<i::Object> recv_obj = Utils::OpenHandle(*recv);
@@ -3519,15 +3992,17 @@
     fun = i::Handle<i::JSFunction>::cast(obj);
   } else {
     EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> delegate =
-        i::Execution::TryGetFunctionDelegate(obj, &has_pending_exception);
+    i::Handle<i::Object> delegate;
+    has_pending_exception = !i::Execution::TryGetFunctionDelegate(
+        isolate, obj).ToHandle(&delegate);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
     fun = i::Handle<i::JSFunction>::cast(delegate);
     recv_obj = obj;
   }
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> returned =
-      i::Execution::Call(fun, recv_obj, argc, args, &has_pending_exception);
+  i::Handle<i::Object> returned;
+  has_pending_exception = !i::Execution::Call(
+      isolate, fun, recv_obj, argc, args, true).ToHandle(&returned);
   EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<Value>());
   return Utils::ToLocal(scope.CloseAndEscape(returned));
 }
@@ -3540,6 +4015,7 @@
              return Local<v8::Object>());
   LOG_API(isolate, "Object::CallAsConstructor");
   ENTER_V8(isolate);
+  i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
   STATIC_ASSERT(sizeof(v8::Handle<v8::Value>) == sizeof(i::Object**));
@@ -3547,29 +4023,45 @@
   if (obj->IsJSFunction()) {
     i::Handle<i::JSFunction> fun = i::Handle<i::JSFunction>::cast(obj);
     EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> returned =
-        i::Execution::New(fun, argc, args, &has_pending_exception);
+    i::Handle<i::Object> returned;
+    has_pending_exception = !i::Execution::New(
+        fun, argc, args).ToHandle(&returned);
     EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<v8::Object>());
     return Utils::ToLocal(scope.CloseAndEscape(
         i::Handle<i::JSObject>::cast(returned)));
   }
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> delegate =
-      i::Execution::TryGetConstructorDelegate(obj, &has_pending_exception);
+  i::Handle<i::Object> delegate;
+  has_pending_exception = !i::Execution::TryGetConstructorDelegate(
+      isolate, obj).ToHandle(&delegate);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Object>());
   if (!delegate->IsUndefined()) {
     i::Handle<i::JSFunction> fun = i::Handle<i::JSFunction>::cast(delegate);
     EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> returned =
-        i::Execution::Call(fun, obj, argc, args, &has_pending_exception);
+    i::Handle<i::Object> returned;
+    has_pending_exception = !i::Execution::Call(
+        isolate, fun, obj, argc, args).ToHandle(&returned);
     EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<v8::Object>());
-    ASSERT(!delegate->IsUndefined());
+    DCHECK(!delegate->IsUndefined());
     return Utils::ToLocal(scope.CloseAndEscape(returned));
   }
   return Local<v8::Object>();
 }
 
 
+Local<Function> Function::New(Isolate* v8_isolate,
+                              FunctionCallback callback,
+                              Local<Value> data,
+                              int length) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  LOG_API(isolate, "Function::New");
+  ENTER_V8(isolate);
+  return FunctionTemplateNew(
+      isolate, callback, data, Local<Signature>(), length, true)->
+      GetFunction();
+}
+
+
 Local<v8::Object> Function::NewInstance() const {
   return NewInstance(0, NULL);
 }
@@ -3582,39 +4074,38 @@
              return Local<v8::Object>());
   LOG_API(isolate, "Function::NewInstance");
   ENTER_V8(isolate);
-  HandleScope scope;
+  i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
+  EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
   i::Handle<i::JSFunction> function = Utils::OpenHandle(this);
   STATIC_ASSERT(sizeof(v8::Handle<v8::Value>) == sizeof(i::Object**));
   i::Handle<i::Object>* args = reinterpret_cast<i::Handle<i::Object>*>(argv);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> returned =
-      i::Execution::New(function, argc, args, &has_pending_exception);
+  i::Handle<i::Object> returned;
+  has_pending_exception = !i::Execution::New(
+      function, argc, args).ToHandle(&returned);
   EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<v8::Object>());
-  return scope.Close(Utils::ToLocal(i::Handle<i::JSObject>::cast(returned)));
+  return scope.Escape(Utils::ToLocal(i::Handle<i::JSObject>::cast(returned)));
 }
 
 
-Local<v8::Value> Function::Call(v8::Handle<v8::Object> recv, int argc,
+Local<v8::Value> Function::Call(v8::Handle<v8::Value> recv, int argc,
                                 v8::Handle<v8::Value> argv[]) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Function::Call()", return Local<v8::Value>());
   LOG_API(isolate, "Function::Call");
   ENTER_V8(isolate);
-  i::Object* raw_result = NULL;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::JSFunction> fun = Utils::OpenHandle(this);
-    i::Handle<i::Object> recv_obj = Utils::OpenHandle(*recv);
-    STATIC_ASSERT(sizeof(v8::Handle<v8::Value>) == sizeof(i::Object**));
-    i::Handle<i::Object>* args = reinterpret_cast<i::Handle<i::Object>*>(argv);
-    EXCEPTION_PREAMBLE(isolate);
-    i::Handle<i::Object> returned =
-        i::Execution::Call(fun, recv_obj, argc, args, &has_pending_exception);
-    EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<Object>());
-    raw_result = *returned;
-  }
-  i::Handle<i::Object> result(raw_result);
-  return Utils::ToLocal(result);
+  i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
+  i::HandleScope scope(isolate);
+  i::Handle<i::JSFunction> fun = Utils::OpenHandle(this);
+  i::Handle<i::Object> recv_obj = Utils::OpenHandle(*recv);
+  STATIC_ASSERT(sizeof(v8::Handle<v8::Value>) == sizeof(i::Object**));
+  i::Handle<i::Object>* args = reinterpret_cast<i::Handle<i::Object>*>(argv);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> returned;
+  has_pending_exception = !i::Execution::Call(
+      isolate, fun, recv_obj, argc, args, true).ToHandle(&returned);
+  EXCEPTION_BAILOUT_CHECK_DO_CALLBACK(isolate, Local<Object>());
+  return Utils::ToLocal(scope.CloseAndEscape(returned));
 }
 
 
@@ -3629,13 +4120,37 @@
 
 Handle<Value> Function::GetName() const {
   i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
-  return Utils::ToLocal(i::Handle<i::Object>(func->shared()->name()));
+  return Utils::ToLocal(i::Handle<i::Object>(func->shared()->name(),
+                                             func->GetIsolate()));
 }
 
 
 Handle<Value> Function::GetInferredName() const {
   i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
-  return Utils::ToLocal(i::Handle<i::Object>(func->shared()->inferred_name()));
+  return Utils::ToLocal(i::Handle<i::Object>(func->shared()->inferred_name(),
+                                             func->GetIsolate()));
+}
+
+
+Handle<Value> Function::GetDisplayName() const {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ON_BAILOUT(isolate, "v8::Function::GetDisplayName()",
+             return ToApiHandle<Primitive>(
+                 isolate->factory()->undefined_value()));
+  ENTER_V8(isolate);
+  i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
+  i::Handle<i::String> property_name =
+      isolate->factory()->InternalizeOneByteString(
+          STATIC_CHAR_VECTOR("displayName"));
+
+  i::Handle<i::Object> value =
+      i::JSObject::GetDataProperty(func, property_name);
+  if (value->IsString()) {
+    i::Handle<i::String> name = i::Handle<i::String>::cast(value);
+    if (name->length() > 0) return Utils::ToLocal(name);
+  }
+
+  return ToApiHandle<Primitive>(isolate->factory()->undefined_value());
 }
 
 
@@ -3643,10 +4158,12 @@
   i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
   if (func->shared()->script()->IsScript()) {
     i::Handle<i::Script> script(i::Script::cast(func->shared()->script()));
+    i::Handle<i::Object> scriptName = i::Script::GetNameOrSourceURL(script);
+    v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(func->GetIsolate());
     v8::ScriptOrigin origin(
-      Utils::ToLocal(i::Handle<i::Object>(script->name())),
-      v8::Integer::New(script->line_offset()->value()),
-      v8::Integer::New(script->column_offset()->value()));
+        Utils::ToLocal(scriptName),
+        v8::Integer::New(isolate, script->line_offset()->value()),
+        v8::Integer::New(isolate, script->column_offset()->value()));
     return origin;
   }
   return v8::ScriptOrigin(Handle<Value>());
@@ -3660,7 +4177,7 @@
   i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
   if (func->shared()->script()->IsScript()) {
     i::Handle<i::Script> script(i::Script::cast(func->shared()->script()));
-    return i::GetScriptLineNumber(script, func->shared()->start_position());
+    return i::Script::GetLineNumber(script, func->shared()->start_position());
   }
   return kLineOffsetNotFound;
 }
@@ -3670,127 +4187,572 @@
   i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
   if (func->shared()->script()->IsScript()) {
     i::Handle<i::Script> script(i::Script::cast(func->shared()->script()));
-    return i::GetScriptColumnNumber(script, func->shared()->start_position());
+    return i::Script::GetColumnNumber(script, func->shared()->start_position());
   }
   return kLineOffsetNotFound;
 }
 
-Handle<Value> Function::GetScriptId() const {
+
+bool Function::IsBuiltin() const {
   i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
-  if (!func->shared()->script()->IsScript())
-    return v8::Undefined();
-  i::Handle<i::Script> script(i::Script::cast(func->shared()->script()));
-  return Utils::ToLocal(i::Handle<i::Object>(script->id()));
+  return func->IsBuiltin();
 }
 
+
+int Function::ScriptId() const {
+  i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
+  if (!func->shared()->script()->IsScript()) {
+    return v8::UnboundScript::kNoScriptId;
+  }
+  i::Handle<i::Script> script(i::Script::cast(func->shared()->script()));
+  return script->id()->value();
+}
+
+
+Local<v8::Value> Function::GetBoundFunction() const {
+  i::Handle<i::JSFunction> func = Utils::OpenHandle(this);
+  if (!func->shared()->bound()) {
+    return v8::Undefined(reinterpret_cast<v8::Isolate*>(func->GetIsolate()));
+  }
+  i::Handle<i::FixedArray> bound_args = i::Handle<i::FixedArray>(
+      i::FixedArray::cast(func->function_bindings()));
+  i::Handle<i::Object> original(
+      bound_args->get(i::JSFunction::kBoundFunctionIndex),
+      func->GetIsolate());
+  return Utils::ToLocal(i::Handle<i::JSFunction>::cast(original));
+}
+
+
 int String::Length() const {
   i::Handle<i::String> str = Utils::OpenHandle(this);
-  if (IsDeadCheck(str->GetIsolate(), "v8::String::Length()")) return 0;
   return str->length();
 }
 
 
+bool String::IsOneByte() const {
+  i::Handle<i::String> str = Utils::OpenHandle(this);
+  return str->HasOnlyOneByteChars();
+}
+
+
+// Helpers for ContainsOnlyOneByteHelper
+template<size_t size> struct OneByteMask;
+template<> struct OneByteMask<4> {
+  static const uint32_t value = 0xFF00FF00;
+};
+template<> struct OneByteMask<8> {
+  static const uint64_t value = V8_2PART_UINT64_C(0xFF00FF00, FF00FF00);
+};
+static const uintptr_t kOneByteMask = OneByteMask<sizeof(uintptr_t)>::value;
+static const uintptr_t kAlignmentMask = sizeof(uintptr_t) - 1;
+static inline bool Unaligned(const uint16_t* chars) {
+  return reinterpret_cast<const uintptr_t>(chars) & kAlignmentMask;
+}
+
+
+static inline const uint16_t* Align(const uint16_t* chars) {
+  return reinterpret_cast<uint16_t*>(
+      reinterpret_cast<uintptr_t>(chars) & ~kAlignmentMask);
+}
+
+class ContainsOnlyOneByteHelper {
+ public:
+  ContainsOnlyOneByteHelper() : is_one_byte_(true) {}
+  bool Check(i::String* string) {
+    i::ConsString* cons_string = i::String::VisitFlat(this, string, 0);
+    if (cons_string == NULL) return is_one_byte_;
+    return CheckCons(cons_string);
+  }
+  void VisitOneByteString(const uint8_t* chars, int length) {
+    // Nothing to do.
+  }
+  void VisitTwoByteString(const uint16_t* chars, int length) {
+    // Accumulated bits.
+    uintptr_t acc = 0;
+    // Align to uintptr_t.
+    const uint16_t* end = chars + length;
+    while (Unaligned(chars) && chars != end) {
+      acc |= *chars++;
+    }
+    // Read word aligned in blocks,
+    // checking the return value at the end of each block.
+    const uint16_t* aligned_end = Align(end);
+    const int increment = sizeof(uintptr_t)/sizeof(uint16_t);
+    const int inner_loops = 16;
+    while (chars + inner_loops*increment < aligned_end) {
+      for (int i = 0; i < inner_loops; i++) {
+        acc |= *reinterpret_cast<const uintptr_t*>(chars);
+        chars += increment;
+      }
+      // Check for early return.
+      if ((acc & kOneByteMask) != 0) {
+        is_one_byte_ = false;
+        return;
+      }
+    }
+    // Read the rest.
+    while (chars != end) {
+      acc |= *chars++;
+    }
+    // Check result.
+    if ((acc & kOneByteMask) != 0) is_one_byte_ = false;
+  }
+
+ private:
+  bool CheckCons(i::ConsString* cons_string) {
+    while (true) {
+      // Check left side if flat.
+      i::String* left = cons_string->first();
+      i::ConsString* left_as_cons =
+          i::String::VisitFlat(this, left, 0);
+      if (!is_one_byte_) return false;
+      // Check right side if flat.
+      i::String* right = cons_string->second();
+      i::ConsString* right_as_cons =
+          i::String::VisitFlat(this, right, 0);
+      if (!is_one_byte_) return false;
+      // Standard recurse/iterate trick.
+      if (left_as_cons != NULL && right_as_cons != NULL) {
+        if (left->length() < right->length()) {
+          CheckCons(left_as_cons);
+          cons_string = right_as_cons;
+        } else {
+          CheckCons(right_as_cons);
+          cons_string = left_as_cons;
+        }
+        // Check fast return.
+        if (!is_one_byte_) return false;
+        continue;
+      }
+      // Descend left in place.
+      if (left_as_cons != NULL) {
+        cons_string = left_as_cons;
+        continue;
+      }
+      // Descend right in place.
+      if (right_as_cons != NULL) {
+        cons_string = right_as_cons;
+        continue;
+      }
+      // Terminate.
+      break;
+    }
+    return is_one_byte_;
+  }
+  bool is_one_byte_;
+  DISALLOW_COPY_AND_ASSIGN(ContainsOnlyOneByteHelper);
+};
+
+
+bool String::ContainsOnlyOneByte() const {
+  i::Handle<i::String> str = Utils::OpenHandle(this);
+  if (str->HasOnlyOneByteChars()) return true;
+  ContainsOnlyOneByteHelper helper;
+  return helper.Check(*str);
+}
+
+
+class Utf8LengthHelper : public i::AllStatic {
+ public:
+  enum State {
+    kEndsWithLeadingSurrogate = 1 << 0,
+    kStartsWithTrailingSurrogate = 1 << 1,
+    kLeftmostEdgeIsCalculated = 1 << 2,
+    kRightmostEdgeIsCalculated = 1 << 3,
+    kLeftmostEdgeIsSurrogate = 1 << 4,
+    kRightmostEdgeIsSurrogate = 1 << 5
+  };
+
+  static const uint8_t kInitialState = 0;
+
+  static inline bool EndsWithSurrogate(uint8_t state) {
+    return state & kEndsWithLeadingSurrogate;
+  }
+
+  static inline bool StartsWithSurrogate(uint8_t state) {
+    return state & kStartsWithTrailingSurrogate;
+  }
+
+  class Visitor {
+   public:
+    Visitor() : utf8_length_(0), state_(kInitialState) {}
+
+    void VisitOneByteString(const uint8_t* chars, int length) {
+      int utf8_length = 0;
+      // Add in length 1 for each non-Latin1 character.
+      for (int i = 0; i < length; i++) {
+        utf8_length += *chars++ >> 7;
+      }
+      // Add in length 1 for each character.
+      utf8_length_ = utf8_length + length;
+      state_ = kInitialState;
+    }
+
+    void VisitTwoByteString(const uint16_t* chars, int length) {
+      int utf8_length = 0;
+      int last_character = unibrow::Utf16::kNoPreviousCharacter;
+      for (int i = 0; i < length; i++) {
+        uint16_t c = chars[i];
+        utf8_length += unibrow::Utf8::Length(c, last_character);
+        last_character = c;
+      }
+      utf8_length_ = utf8_length;
+      uint8_t state = 0;
+      if (unibrow::Utf16::IsTrailSurrogate(chars[0])) {
+        state |= kStartsWithTrailingSurrogate;
+      }
+      if (unibrow::Utf16::IsLeadSurrogate(chars[length-1])) {
+        state |= kEndsWithLeadingSurrogate;
+      }
+      state_ = state;
+    }
+
+    static i::ConsString* VisitFlat(i::String* string,
+                                    int* length,
+                                    uint8_t* state) {
+      Visitor visitor;
+      i::ConsString* cons_string = i::String::VisitFlat(&visitor, string);
+      *length = visitor.utf8_length_;
+      *state = visitor.state_;
+      return cons_string;
+    }
+
+   private:
+    int utf8_length_;
+    uint8_t state_;
+    DISALLOW_COPY_AND_ASSIGN(Visitor);
+  };
+
+  static inline void MergeLeafLeft(int* length,
+                                   uint8_t* state,
+                                   uint8_t leaf_state) {
+    bool edge_surrogate = StartsWithSurrogate(leaf_state);
+    if (!(*state & kLeftmostEdgeIsCalculated)) {
+      DCHECK(!(*state & kLeftmostEdgeIsSurrogate));
+      *state |= kLeftmostEdgeIsCalculated
+          | (edge_surrogate ? kLeftmostEdgeIsSurrogate : 0);
+    } else if (EndsWithSurrogate(*state) && edge_surrogate) {
+      *length -= unibrow::Utf8::kBytesSavedByCombiningSurrogates;
+    }
+    if (EndsWithSurrogate(leaf_state)) {
+      *state |= kEndsWithLeadingSurrogate;
+    } else {
+      *state &= ~kEndsWithLeadingSurrogate;
+    }
+  }
+
+  static inline void MergeLeafRight(int* length,
+                                    uint8_t* state,
+                                    uint8_t leaf_state) {
+    bool edge_surrogate = EndsWithSurrogate(leaf_state);
+    if (!(*state & kRightmostEdgeIsCalculated)) {
+      DCHECK(!(*state & kRightmostEdgeIsSurrogate));
+      *state |= (kRightmostEdgeIsCalculated
+                 | (edge_surrogate ? kRightmostEdgeIsSurrogate : 0));
+    } else if (edge_surrogate && StartsWithSurrogate(*state)) {
+      *length -= unibrow::Utf8::kBytesSavedByCombiningSurrogates;
+    }
+    if (StartsWithSurrogate(leaf_state)) {
+      *state |= kStartsWithTrailingSurrogate;
+    } else {
+      *state &= ~kStartsWithTrailingSurrogate;
+    }
+  }
+
+  static inline void MergeTerminal(int* length,
+                                   uint8_t state,
+                                   uint8_t* state_out) {
+    DCHECK((state & kLeftmostEdgeIsCalculated) &&
+           (state & kRightmostEdgeIsCalculated));
+    if (EndsWithSurrogate(state) && StartsWithSurrogate(state)) {
+      *length -= unibrow::Utf8::kBytesSavedByCombiningSurrogates;
+    }
+    *state_out = kInitialState |
+        (state & kLeftmostEdgeIsSurrogate ? kStartsWithTrailingSurrogate : 0) |
+        (state & kRightmostEdgeIsSurrogate ? kEndsWithLeadingSurrogate : 0);
+  }
+
+  static int Calculate(i::ConsString* current, uint8_t* state_out) {
+    using namespace internal;
+    int total_length = 0;
+    uint8_t state = kInitialState;
+    while (true) {
+      i::String* left = current->first();
+      i::String* right = current->second();
+      uint8_t right_leaf_state;
+      uint8_t left_leaf_state;
+      int leaf_length;
+      ConsString* left_as_cons =
+          Visitor::VisitFlat(left, &leaf_length, &left_leaf_state);
+      if (left_as_cons == NULL) {
+        total_length += leaf_length;
+        MergeLeafLeft(&total_length, &state, left_leaf_state);
+      }
+      ConsString* right_as_cons =
+          Visitor::VisitFlat(right, &leaf_length, &right_leaf_state);
+      if (right_as_cons == NULL) {
+        total_length += leaf_length;
+        MergeLeafRight(&total_length, &state, right_leaf_state);
+        if (left_as_cons != NULL) {
+          // 1 Leaf node. Descend in place.
+          current = left_as_cons;
+          continue;
+        } else {
+          // Terminal node.
+          MergeTerminal(&total_length, state, state_out);
+          return total_length;
+        }
+      } else if (left_as_cons == NULL) {
+        // 1 Leaf node. Descend in place.
+        current = right_as_cons;
+        continue;
+      }
+      // Both strings are ConsStrings.
+      // Recurse on smallest.
+      if (left->length() < right->length()) {
+        total_length += Calculate(left_as_cons, &left_leaf_state);
+        MergeLeafLeft(&total_length, &state, left_leaf_state);
+        current = right_as_cons;
+      } else {
+        total_length += Calculate(right_as_cons, &right_leaf_state);
+        MergeLeafRight(&total_length, &state, right_leaf_state);
+        current = left_as_cons;
+      }
+    }
+    UNREACHABLE();
+    return 0;
+  }
+
+  static inline int Calculate(i::ConsString* current) {
+    uint8_t state = kInitialState;
+    return Calculate(current, &state);
+  }
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Utf8LengthHelper);
+};
+
+
+static int Utf8Length(i::String* str, i::Isolate* isolate) {
+  int length = str->length();
+  if (length == 0) return 0;
+  uint8_t state;
+  i::ConsString* cons_string =
+      Utf8LengthHelper::Visitor::VisitFlat(str, &length, &state);
+  if (cons_string == NULL) return length;
+  return Utf8LengthHelper::Calculate(cons_string);
+}
+
+
 int String::Utf8Length() const {
   i::Handle<i::String> str = Utils::OpenHandle(this);
-  if (IsDeadCheck(str->GetIsolate(), "v8::String::Utf8Length()")) return 0;
-  return i::Utf8Length(str);
+  i::Isolate* isolate = str->GetIsolate();
+  return v8::Utf8Length(*str, isolate);
 }
 
 
-// Will fail with a negative answer if the recursion depth is too high.
-static int RecursivelySerializeToUtf8(i::String* string,
-                                      char* buffer,
-                                      int start,
-                                      int end,
-                                      int recursion_budget,
-                                      int32_t previous_character,
-                                      int32_t* last_character) {
-  int utf8_bytes = 0;
-  while (true) {
-    if (string->IsAsciiRepresentation()) {
-      i::String::WriteToFlat(string, buffer, start, end);
-      *last_character = unibrow::Utf16::kNoPreviousCharacter;
-      return utf8_bytes + end - start;
+class Utf8WriterVisitor {
+ public:
+  Utf8WriterVisitor(
+      char* buffer,
+      int capacity,
+      bool skip_capacity_check,
+      bool replace_invalid_utf8)
+    : early_termination_(false),
+      last_character_(unibrow::Utf16::kNoPreviousCharacter),
+      buffer_(buffer),
+      start_(buffer),
+      capacity_(capacity),
+      skip_capacity_check_(capacity == -1 || skip_capacity_check),
+      replace_invalid_utf8_(replace_invalid_utf8),
+      utf16_chars_read_(0) {
+  }
+
+  static int WriteEndCharacter(uint16_t character,
+                               int last_character,
+                               int remaining,
+                               char* const buffer,
+                               bool replace_invalid_utf8) {
+    using namespace unibrow;
+    DCHECK(remaining > 0);
+    // We can't use a local buffer here because Encode needs to modify
+    // previous characters in the stream.  We know, however, that
+    // exactly one character will be advanced.
+    if (Utf16::IsSurrogatePair(last_character, character)) {
+      int written = Utf8::Encode(buffer,
+                                 character,
+                                 last_character,
+                                 replace_invalid_utf8);
+      DCHECK(written == 1);
+      return written;
     }
-    switch (i::StringShape(string).representation_tag()) {
-      case i::kExternalStringTag: {
-        const uint16_t* data = i::ExternalTwoByteString::cast(string)->
-          ExternalTwoByteStringGetData(0);
-        char* current = buffer;
-        for (int i = start; i < end; i++) {
-          uint16_t character = data[i];
-          current +=
-              unibrow::Utf8::Encode(current, character, previous_character);
-          previous_character = character;
-        }
-        *last_character = previous_character;
-        return static_cast<int>(utf8_bytes + current - buffer);
+    // Use a scratch buffer to check the required characters.
+    char temp_buffer[Utf8::kMaxEncodedSize];
+    // Can't encode using last_character as gcc has array bounds issues.
+    int written = Utf8::Encode(temp_buffer,
+                               character,
+                               Utf16::kNoPreviousCharacter,
+                               replace_invalid_utf8);
+    // Won't fit.
+    if (written > remaining) return 0;
+    // Copy over the character from temp_buffer.
+    for (int j = 0; j < written; j++) {
+      buffer[j] = temp_buffer[j];
+    }
+    return written;
+  }
+
+  // Visit writes out a group of code units (chars) of a v8::String to the
+  // internal buffer_. This is done in two phases. The first phase calculates a
+  // pesimistic estimate (writable_length) on how many code units can be safely
+  // written without exceeding the buffer capacity and without writing the last
+  // code unit (it could be a lead surrogate). The estimated number of code
+  // units is then written out in one go, and the reported byte usage is used
+  // to correct the estimate. This is repeated until the estimate becomes <= 0
+  // or all code units have been written out. The second phase writes out code
+  // units until the buffer capacity is reached, would be exceeded by the next
+  // unit, or all units have been written out.
+  template<typename Char>
+  void Visit(const Char* chars, const int length) {
+    using namespace unibrow;
+    DCHECK(!early_termination_);
+    if (length == 0) return;
+    // Copy state to stack.
+    char* buffer = buffer_;
+    int last_character =
+        sizeof(Char) == 1 ? Utf16::kNoPreviousCharacter : last_character_;
+    int i = 0;
+    // Do a fast loop where there is no exit capacity check.
+    while (true) {
+      int fast_length;
+      if (skip_capacity_check_) {
+        fast_length = length;
+      } else {
+        int remaining_capacity = capacity_ - static_cast<int>(buffer - start_);
+        // Need enough space to write everything but one character.
+        STATIC_ASSERT(Utf16::kMaxExtraUtf8BytesForOneUtf16CodeUnit == 3);
+        int max_size_per_char =  sizeof(Char) == 1 ? 2 : 3;
+        int writable_length =
+            (remaining_capacity - max_size_per_char)/max_size_per_char;
+        // Need to drop into slow loop.
+        if (writable_length <= 0) break;
+        fast_length = i + writable_length;
+        if (fast_length > length) fast_length = length;
       }
-      case i::kSeqStringTag: {
-        const uint16_t* data =
-            i::SeqTwoByteString::cast(string)->SeqTwoByteStringGetData(0);
-        char* current = buffer;
-        for (int i = start; i < end; i++) {
-          uint16_t character = data[i];
-          current +=
-              unibrow::Utf8::Encode(current, character, previous_character);
-          previous_character = character;
+      // Write the characters to the stream.
+      if (sizeof(Char) == 1) {
+        for (; i < fast_length; i++) {
+          buffer +=
+              Utf8::EncodeOneByte(buffer, static_cast<uint8_t>(*chars++));
+          DCHECK(capacity_ == -1 || (buffer - start_) <= capacity_);
         }
-        *last_character = previous_character;
-        return static_cast<int>(utf8_bytes + current - buffer);
-      }
-      case i::kSlicedStringTag: {
-        i::SlicedString* slice = i::SlicedString::cast(string);
-        unsigned offset = slice->offset();
-        string = slice->parent();
-        start += offset;
-        end += offset;
-        continue;
-      }
-      case i::kConsStringTag: {
-        i::ConsString* cons_string = i::ConsString::cast(string);
-        i::String* first = cons_string->first();
-        int boundary = first->length();
-        if (start >= boundary) {
-          // Only need RHS.
-          string = cons_string->second();
-          start -= boundary;
-          end -= boundary;
-          continue;
-        } else if (end <= boundary) {
-          // Only need LHS.
-          string = first;
-        } else {
-          if (recursion_budget == 0) return -1;
-          int extra_utf8_bytes =
-              RecursivelySerializeToUtf8(first,
-                                         buffer,
-                                         start,
-                                         boundary,
-                                         recursion_budget - 1,
-                                         previous_character,
-                                         &previous_character);
-          if (extra_utf8_bytes < 0) return extra_utf8_bytes;
-          buffer += extra_utf8_bytes;
-          utf8_bytes += extra_utf8_bytes;
-          string = cons_string->second();
-          start = 0;
-          end -= boundary;
+      } else {
+        for (; i < fast_length; i++) {
+          uint16_t character = *chars++;
+          buffer += Utf8::Encode(buffer,
+                                 character,
+                                 last_character,
+                                 replace_invalid_utf8_);
+          last_character = character;
+          DCHECK(capacity_ == -1 || (buffer - start_) <= capacity_);
         }
       }
+      // Array is fully written. Exit.
+      if (fast_length == length) {
+        // Write state back out to object.
+        last_character_ = last_character;
+        buffer_ = buffer;
+        utf16_chars_read_ += length;
+        return;
+      }
     }
+    DCHECK(!skip_capacity_check_);
+    // Slow loop. Must check capacity on each iteration.
+    int remaining_capacity = capacity_ - static_cast<int>(buffer - start_);
+    DCHECK(remaining_capacity >= 0);
+    for (; i < length && remaining_capacity > 0; i++) {
+      uint16_t character = *chars++;
+      // remaining_capacity is <= 3 bytes at this point, so we do not write out
+      // an umatched lead surrogate.
+      if (replace_invalid_utf8_ && Utf16::IsLeadSurrogate(character)) {
+        early_termination_ = true;
+        break;
+      }
+      int written = WriteEndCharacter(character,
+                                      last_character,
+                                      remaining_capacity,
+                                      buffer,
+                                      replace_invalid_utf8_);
+      if (written == 0) {
+        early_termination_ = true;
+        break;
+      }
+      buffer += written;
+      remaining_capacity -= written;
+      last_character = character;
+    }
+    // Write state back out to object.
+    last_character_ = last_character;
+    buffer_ = buffer;
+    utf16_chars_read_ += i;
   }
-  UNREACHABLE();
-  return 0;
-}
+
+  inline bool IsDone() {
+    return early_termination_;
+  }
+
+  inline void VisitOneByteString(const uint8_t* chars, int length) {
+    Visit(chars, length);
+  }
+
+  inline void VisitTwoByteString(const uint16_t* chars, int length) {
+    Visit(chars, length);
+  }
+
+  int CompleteWrite(bool write_null, int* utf16_chars_read_out) {
+    // Write out number of utf16 characters written to the stream.
+    if (utf16_chars_read_out != NULL) {
+      *utf16_chars_read_out = utf16_chars_read_;
+    }
+    // Only null terminate if all of the string was written and there's space.
+    if (write_null &&
+        !early_termination_ &&
+        (capacity_ == -1 || (buffer_ - start_) < capacity_)) {
+      *buffer_++ = '\0';
+    }
+    return static_cast<int>(buffer_ - start_);
+  }
+
+ private:
+  bool early_termination_;
+  int last_character_;
+  char* buffer_;
+  char* const start_;
+  int capacity_;
+  bool const skip_capacity_check_;
+  bool const replace_invalid_utf8_;
+  int utf16_chars_read_;
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Utf8WriterVisitor);
+};
 
 
-bool String::MayContainNonAscii() const {
-  i::Handle<i::String> str = Utils::OpenHandle(this);
-  if (IsDeadCheck(str->GetIsolate(), "v8::String::MayContainNonAscii()")) {
-    return false;
+static bool RecursivelySerializeToUtf8(i::String* current,
+                                       Utf8WriterVisitor* writer,
+                                       int recursion_budget) {
+  while (!writer->IsDone()) {
+    i::ConsString* cons_string = i::String::VisitFlat(writer, current);
+    if (cons_string == NULL) return true;  // Leaf node.
+    if (recursion_budget <= 0) return false;
+    // Must write the left branch first.
+    i::String* first = cons_string->first();
+    bool success = RecursivelySerializeToUtf8(first,
+                                              writer,
+                                              recursion_budget - 1);
+    if (!success) return false;
+    // Inline tail recurse for right branch.
+    current = cons_string->second();
   }
-  return !str->HasOnlyAsciiChars();
+  return true;
 }
 
 
@@ -3799,188 +4761,75 @@
                       int* nchars_ref,
                       int options) const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::String::WriteUtf8()")) return 0;
   LOG_API(isolate, "String::WriteUtf8");
   ENTER_V8(isolate);
   i::Handle<i::String> str = Utils::OpenHandle(this);
-  int string_length = str->length();
-  if (str->IsAsciiRepresentation()) {
-    int len;
-    if (capacity == -1) {
-      capacity = str->length() + 1;
-      len = string_length;
-    } else {
-      len = i::Min(capacity, str->length());
-    }
-    i::String::WriteToFlat(*str, buffer, 0, len);
-    if (nchars_ref != NULL) *nchars_ref = len;
-    if (!(options & NO_NULL_TERMINATION) && capacity > len) {
-      buffer[len] = '\0';
-      return len + 1;
-    }
-    return len;
+  if (options & HINT_MANY_WRITES_EXPECTED) {
+    str = i::String::Flatten(str);  // Flatten the string for efficiency.
   }
-
-  if (capacity == -1 || capacity / 3 >= string_length) {
-    int32_t previous = unibrow::Utf16::kNoPreviousCharacter;
+  const int string_length = str->length();
+  bool write_null = !(options & NO_NULL_TERMINATION);
+  bool replace_invalid_utf8 = (options & REPLACE_INVALID_UTF8);
+  int max16BitCodeUnitSize = unibrow::Utf8::kMax16BitCodeUnitSize;
+  // First check if we can just write the string without checking capacity.
+  if (capacity == -1 || capacity / max16BitCodeUnitSize >= string_length) {
+    Utf8WriterVisitor writer(buffer, capacity, true, replace_invalid_utf8);
     const int kMaxRecursion = 100;
-    int utf8_bytes =
-        RecursivelySerializeToUtf8(*str,
-                                   buffer,
-                                   0,
-                                   string_length,
-                                   kMaxRecursion,
-                                   previous,
-                                   &previous);
-    if (utf8_bytes >= 0) {
-      // Success serializing with recursion.
-      if ((options & NO_NULL_TERMINATION) == 0 &&
-          (capacity > utf8_bytes || capacity == -1)) {
-        buffer[utf8_bytes++] = '\0';
-      }
-      if (nchars_ref != NULL) *nchars_ref = string_length;
-      return utf8_bytes;
-    }
-    FlattenString(str);
-    // Recurse once.  This time around the string is flat and the serializing
-    // with recursion will certainly succeed.
-    return WriteUtf8(buffer, capacity, nchars_ref, options);
+    bool success = RecursivelySerializeToUtf8(*str, &writer, kMaxRecursion);
+    if (success) return writer.CompleteWrite(write_null, nchars_ref);
   } else if (capacity >= string_length) {
-    // First check that the buffer is large enough.  If it is, then recurse
-    // once without a capacity limit, which will get into the other branch of
-    // this 'if'.
-    int utf8_bytes = i::Utf8Length(str);
-    if ((options & NO_NULL_TERMINATION) == 0) utf8_bytes++;
+    // First check that the buffer is large enough.
+    int utf8_bytes = v8::Utf8Length(*str, str->GetIsolate());
     if (utf8_bytes <= capacity) {
+      // one-byte fast path.
+      if (utf8_bytes == string_length) {
+        WriteOneByte(reinterpret_cast<uint8_t*>(buffer), 0, capacity, options);
+        if (nchars_ref != NULL) *nchars_ref = string_length;
+        if (write_null && (utf8_bytes+1 <= capacity)) {
+          return string_length + 1;
+        }
+        return string_length;
+      }
+      if (write_null && (utf8_bytes+1 > capacity)) {
+        options |= NO_NULL_TERMINATION;
+      }
+      // Recurse once without a capacity limit.
+      // This will get into the first branch above.
+      // TODO(dcarney) Check max left rec. in Utf8Length and fall through.
       return WriteUtf8(buffer, -1, nchars_ref, options);
     }
   }
-
-  // Slow case.
-  i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
-  isolate->string_tracker()->RecordWrite(str);
-  if (options & HINT_MANY_WRITES_EXPECTED) {
-    // Flatten the string for efficiency.  This applies whether we are
-    // using StringInputBuffer or Get(i) to access the characters.
-    FlattenString(str);
-  }
-  write_input_buffer.Reset(0, *str);
-  int len = str->length();
-  // Encode the first K - 3 bytes directly into the buffer since we
-  // know there's room for them.  If no capacity is given we copy all
-  // of them here.
-  int fast_end = capacity - (unibrow::Utf8::kMaxEncodedSize - 1);
-  int i;
-  int pos = 0;
-  int nchars = 0;
-  int previous = unibrow::Utf16::kNoPreviousCharacter;
-  for (i = 0; i < len && (capacity == -1 || pos < fast_end); i++) {
-    i::uc32 c = write_input_buffer.GetNext();
-    int written = unibrow::Utf8::Encode(buffer + pos, c, previous);
-    pos += written;
-    nchars++;
-    previous = c;
-  }
-  if (i < len) {
-    // For the last characters we need to check the length for each one
-    // because they may be longer than the remaining space in the
-    // buffer.
-    char intermediate[unibrow::Utf8::kMaxEncodedSize];
-    for (; i < len && pos < capacity; i++) {
-      i::uc32 c = write_input_buffer.GetNext();
-      if (unibrow::Utf16::IsTrailSurrogate(c) &&
-          unibrow::Utf16::IsLeadSurrogate(previous)) {
-        // We can't use the intermediate buffer here because the encoding
-        // of surrogate pairs is done under assumption that you can step
-        // back and fix the UTF8 stream.  Luckily we only need space for one
-        // more byte, so there is always space.
-        ASSERT(pos < capacity);
-        int written = unibrow::Utf8::Encode(buffer + pos, c, previous);
-        ASSERT(written == 1);
-        pos += written;
-        nchars++;
-      } else {
-        int written =
-            unibrow::Utf8::Encode(intermediate,
-                                  c,
-                                  unibrow::Utf16::kNoPreviousCharacter);
-        if (pos + written <= capacity) {
-          for (int j = 0; j < written; j++)
-            buffer[pos + j] = intermediate[j];
-          pos += written;
-          nchars++;
-        } else {
-          // We've reached the end of the buffer
-          break;
-        }
-      }
-      previous = c;
-    }
-  }
-  if (nchars_ref != NULL) *nchars_ref = nchars;
-  if (!(options & NO_NULL_TERMINATION) &&
-      (i == len && (capacity == -1 || pos < capacity)))
-    buffer[pos++] = '\0';
-  return pos;
+  // Recursive slow path can potentially be unreasonable slow. Flatten.
+  str = i::String::Flatten(str);
+  Utf8WriterVisitor writer(buffer, capacity, false, replace_invalid_utf8);
+  i::String::VisitFlat(&writer, *str);
+  return writer.CompleteWrite(write_null, nchars_ref);
 }
 
 
-int String::WriteAscii(char* buffer,
-                       int start,
-                       int length,
-                       int options) const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::String::WriteAscii()")) return 0;
-  LOG_API(isolate, "String::WriteAscii");
-  ENTER_V8(isolate);
-  i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
-  ASSERT(start >= 0 && length >= -1);
-  i::Handle<i::String> str = Utils::OpenHandle(this);
-  isolate->string_tracker()->RecordWrite(str);
-  if (options & HINT_MANY_WRITES_EXPECTED) {
-    // Flatten the string for efficiency.  This applies whether we are
-    // using StringInputBuffer or Get(i) to access the characters.
-    str->TryFlatten();
-  }
-  int end = length;
-  if ( (length == -1) || (length > str->length() - start) )
-    end = str->length() - start;
-  if (end < 0) return 0;
-  write_input_buffer.Reset(start, *str);
-  int i;
-  for (i = 0; i < end; i++) {
-    char c = static_cast<char>(write_input_buffer.GetNext());
-    if (c == '\0') c = ' ';
-    buffer[i] = c;
-  }
-  if (!(options & NO_NULL_TERMINATION) && (length == -1 || i < length))
-    buffer[i] = '\0';
-  return i;
-}
-
-
-int String::Write(uint16_t* buffer,
-                  int start,
-                  int length,
-                  int options) const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::String::Write()")) return 0;
+template<typename CharType>
+static inline int WriteHelper(const String* string,
+                              CharType* buffer,
+                              int start,
+                              int length,
+                              int options) {
+  i::Isolate* isolate = Utils::OpenHandle(string)->GetIsolate();
   LOG_API(isolate, "String::Write");
   ENTER_V8(isolate);
-  ASSERT(start >= 0 && length >= -1);
-  i::Handle<i::String> str = Utils::OpenHandle(this);
+  DCHECK(start >= 0 && length >= -1);
+  i::Handle<i::String> str = Utils::OpenHandle(string);
   isolate->string_tracker()->RecordWrite(str);
-  if (options & HINT_MANY_WRITES_EXPECTED) {
+  if (options & String::HINT_MANY_WRITES_EXPECTED) {
     // Flatten the string for efficiency.  This applies whether we are
-    // using StringInputBuffer or Get(i) to access the characters.
-    str->TryFlatten();
+    // using StringCharacterStream or Get(i) to access the characters.
+    str = i::String::Flatten(str);
   }
   int end = start + length;
   if ((length == -1) || (length > str->length() - start) )
     end = str->length();
   if (end < 0) return 0;
   i::String::WriteToFlat(*str, buffer, start, end);
-  if (!(options & NO_NULL_TERMINATION) &&
+  if (!(options & String::NO_NULL_TERMINATION) &&
       (length == -1 || end - start < length)) {
     buffer[end - start] = '\0';
   }
@@ -3988,22 +4837,31 @@
 }
 
 
+int String::WriteOneByte(uint8_t* buffer,
+                         int start,
+                         int length,
+                         int options) const {
+  return WriteHelper(this, buffer, start, length, options);
+}
+
+
+int String::Write(uint16_t* buffer,
+                  int start,
+                  int length,
+                  int options) const {
+  return WriteHelper(this, buffer, start, length, options);
+}
+
+
 bool v8::String::IsExternal() const {
   i::Handle<i::String> str = Utils::OpenHandle(this);
-  if (IsDeadCheck(str->GetIsolate(), "v8::String::IsExternal()")) {
-    return false;
-  }
-  EnsureInitializedForIsolate(str->GetIsolate(), "v8::String::IsExternal()");
   return i::StringShape(*str).IsExternalTwoByte();
 }
 
 
-bool v8::String::IsExternalAscii() const {
+bool v8::String::IsExternalOneByte() const {
   i::Handle<i::String> str = Utils::OpenHandle(this);
-  if (IsDeadCheck(str->GetIsolate(), "v8::String::IsExternalAscii()")) {
-    return false;
-  }
-  return i::StringShape(*str).IsExternalAscii();
+  return i::StringShape(*str).IsExternalOneByte();
 }
 
 
@@ -4021,40 +4879,68 @@
   CHECK_EQ(expected, value);
 }
 
-
-const v8::String::ExternalAsciiStringResource*
-      v8::String::GetExternalAsciiStringResource() const {
+void v8::String::VerifyExternalStringResourceBase(
+    v8::String::ExternalStringResourceBase* value, Encoding encoding) const {
   i::Handle<i::String> str = Utils::OpenHandle(this);
-  if (IsDeadCheck(str->GetIsolate(),
-                  "v8::String::GetExternalAsciiStringResource()")) {
-    return NULL;
-  }
-  if (i::StringShape(*str).IsExternalAscii()) {
+  const v8::String::ExternalStringResourceBase* expected;
+  Encoding expectedEncoding;
+  if (i::StringShape(*str).IsExternalOneByte()) {
     const void* resource =
-        i::Handle<i::ExternalAsciiString>::cast(str)->resource();
-    return reinterpret_cast<const ExternalAsciiStringResource*>(resource);
+        i::Handle<i::ExternalOneByteString>::cast(str)->resource();
+    expected = reinterpret_cast<const ExternalStringResourceBase*>(resource);
+    expectedEncoding = ONE_BYTE_ENCODING;
+  } else if (i::StringShape(*str).IsExternalTwoByte()) {
+    const void* resource =
+        i::Handle<i::ExternalTwoByteString>::cast(str)->resource();
+    expected = reinterpret_cast<const ExternalStringResourceBase*>(resource);
+    expectedEncoding = TWO_BYTE_ENCODING;
+  } else {
+    expected = NULL;
+    expectedEncoding =
+        str->IsOneByteRepresentation() ? ONE_BYTE_ENCODING : TWO_BYTE_ENCODING;
+  }
+  CHECK_EQ(expected, value);
+  CHECK_EQ(expectedEncoding, encoding);
+}
+
+const v8::String::ExternalOneByteStringResource*
+v8::String::GetExternalOneByteStringResource() const {
+  i::Handle<i::String> str = Utils::OpenHandle(this);
+  if (i::StringShape(*str).IsExternalOneByte()) {
+    const void* resource =
+        i::Handle<i::ExternalOneByteString>::cast(str)->resource();
+    return reinterpret_cast<const ExternalOneByteStringResource*>(resource);
   } else {
     return NULL;
   }
 }
 
 
+Local<Value> Symbol::Name() const {
+  i::Handle<i::Symbol> sym = Utils::OpenHandle(this);
+  i::Handle<i::Object> name(sym->name(), sym->GetIsolate());
+  return Utils::ToLocal(name);
+}
+
+
+Local<Value> Private::Name() const {
+  return reinterpret_cast<const Symbol*>(this)->Name();
+}
+
+
 double Number::Value() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Number::Value()")) return 0;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   return obj->Number();
 }
 
 
 bool Boolean::Value() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Boolean::Value()")) return false;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   return obj->IsTrue();
 }
 
 
 int64_t Integer::Value() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Integer::Value()")) return 0;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsSmi()) {
     return i::Smi::cast(*obj)->value();
@@ -4065,7 +4951,6 @@
 
 
 int32_t Int32::Value() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Int32::Value()")) return 0;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsSmi()) {
     return i::Smi::cast(*obj)->value();
@@ -4076,7 +4961,6 @@
 
 
 uint32_t Uint32::Value() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Uint32::Value()")) return 0;
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (obj->IsSmi()) {
     return i::Smi::cast(*obj)->value();
@@ -4088,114 +4972,103 @@
 
 int v8::Object::InternalFieldCount() {
   i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
-  if (IsDeadCheck(obj->GetIsolate(), "v8::Object::InternalFieldCount()")) {
-    return 0;
-  }
   return obj->GetInternalFieldCount();
 }
 
 
-Local<Value> v8::Object::CheckedGetInternalField(int index) {
+static bool InternalFieldOK(i::Handle<i::JSObject> obj,
+                            int index,
+                            const char* location) {
+  return Utils::ApiCheck(index < obj->GetInternalFieldCount(),
+                         location,
+                         "Internal field out of bounds");
+}
+
+
+Local<Value> v8::Object::SlowGetInternalField(int index) {
   i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
-  if (IsDeadCheck(obj->GetIsolate(), "v8::Object::GetInternalField()")) {
-    return Local<Value>();
-  }
-  if (!ApiCheck(index < obj->GetInternalFieldCount(),
-                "v8::Object::GetInternalField()",
-                "Reading internal field out of bounds")) {
-    return Local<Value>();
-  }
-  i::Handle<i::Object> value(obj->GetInternalField(index));
-  Local<Value> result = Utils::ToLocal(value);
-#ifdef DEBUG
-  Local<Value> unchecked = UncheckedGetInternalField(index);
-  ASSERT(unchecked.IsEmpty() || (unchecked == result));
-#endif
-  return result;
+  const char* location = "v8::Object::GetInternalField()";
+  if (!InternalFieldOK(obj, index, location)) return Local<Value>();
+  i::Handle<i::Object> value(obj->GetInternalField(index), obj->GetIsolate());
+  return Utils::ToLocal(value);
 }
 
 
 void v8::Object::SetInternalField(int index, v8::Handle<Value> value) {
   i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
-  i::Isolate* isolate = obj->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Object::SetInternalField()")) {
-    return;
-  }
-  if (!ApiCheck(index < obj->GetInternalFieldCount(),
-                "v8::Object::SetInternalField()",
-                "Writing internal field out of bounds")) {
-    return;
-  }
-  ENTER_V8(isolate);
+  const char* location = "v8::Object::SetInternalField()";
+  if (!InternalFieldOK(obj, index, location)) return;
   i::Handle<i::Object> val = Utils::OpenHandle(*value);
   obj->SetInternalField(index, *val);
+  DCHECK_EQ(value, GetInternalField(index));
 }
 
 
-static bool CanBeEncodedAsSmi(void* ptr) {
-  const uintptr_t address = reinterpret_cast<uintptr_t>(ptr);
-  return ((address & i::kEncodablePointerMask) == 0);
+void* v8::Object::SlowGetAlignedPointerFromInternalField(int index) {
+  i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
+  const char* location = "v8::Object::GetAlignedPointerFromInternalField()";
+  if (!InternalFieldOK(obj, index, location)) return NULL;
+  return DecodeSmiToAligned(obj->GetInternalField(index), location);
 }
 
 
-static i::Smi* EncodeAsSmi(void* ptr) {
-  ASSERT(CanBeEncodedAsSmi(ptr));
-  const uintptr_t address = reinterpret_cast<uintptr_t>(ptr);
-  i::Smi* result = reinterpret_cast<i::Smi*>(address << i::kPointerToSmiShift);
-  ASSERT(i::Internals::HasSmiTag(result));
-  ASSERT_EQ(result, i::Smi::FromInt(result->value()));
-  ASSERT_EQ(ptr, i::Internals::GetExternalPointerFromSmi(result));
-  return result;
+void v8::Object::SetAlignedPointerInInternalField(int index, void* value) {
+  i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
+  const char* location = "v8::Object::SetAlignedPointerInInternalField()";
+  if (!InternalFieldOK(obj, index, location)) return;
+  obj->SetInternalField(index, EncodeAlignedAsSmi(value, location));
+  DCHECK_EQ(value, GetAlignedPointerFromInternalField(index));
 }
 
 
-void v8::Object::SetPointerInInternalField(int index, void* value) {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  ENTER_V8(isolate);
-  if (CanBeEncodedAsSmi(value)) {
-    Utils::OpenHandle(this)->SetInternalField(index, EncodeAsSmi(value));
-  } else {
-    HandleScope scope;
-    i::Handle<i::Foreign> foreign =
-        isolate->factory()->NewForeign(
-            reinterpret_cast<i::Address>(value), i::TENURED);
-    if (!foreign.is_null())
-        Utils::OpenHandle(this)->SetInternalField(index, *foreign);
-  }
-  ASSERT_EQ(value, GetPointerFromInternalField(index));
+static void* ExternalValue(i::Object* obj) {
+  // Obscure semantics for undefined, but somehow checked in our unit tests...
+  if (obj->IsUndefined()) return NULL;
+  i::Object* foreign = i::JSObject::cast(obj)->GetInternalField(0);
+  return i::Foreign::cast(foreign)->foreign_address();
 }
 
 
 // --- E n v i r o n m e n t ---
 
 
-bool v8::V8::Initialize() {
-  i::Isolate* isolate = i::Isolate::UncheckedCurrent();
-  if (isolate != NULL && isolate->IsInitialized()) {
-    return true;
-  }
-  return InitializeHelper();
+void v8::V8::InitializePlatform(Platform* platform) {
+  i::V8::InitializePlatform(platform);
 }
 
 
-void v8::V8::SetEntropySource(EntropySource source) {
-  i::V8::SetEntropySource(source);
+void v8::V8::ShutdownPlatform() {
+  i::V8::ShutdownPlatform();
+}
+
+
+bool v8::V8::Initialize() {
+  i::V8::Initialize();
+  return true;
+}
+
+
+void v8::V8::SetEntropySource(EntropySource entropy_source) {
+  base::RandomNumberGenerator::SetEntropySource(entropy_source);
 }
 
 
 void v8::V8::SetReturnAddressLocationResolver(
-      ReturnAddressLocationResolver return_address_resolver) {
+    ReturnAddressLocationResolver return_address_resolver) {
   i::V8::SetReturnAddressLocationResolver(return_address_resolver);
 }
 
+void v8::V8::SetArrayBufferAllocator(
+    ArrayBuffer::Allocator* allocator) {
+  if (!Utils::ApiCheck(i::V8::ArrayBufferAllocator() == NULL,
+                       "v8::V8::SetArrayBufferAllocator",
+                       "ArrayBufferAllocator might only be set once"))
+    return;
+  i::V8::SetArrayBufferAllocator(allocator);
+}
+
 
 bool v8::V8::Dispose() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!ApiCheck(isolate != NULL && isolate->IsDefaultIsolate(),
-                "v8::V8::Dispose()",
-                "Use v8::Isolate::Dispose() for a non-default isolate.")) {
-    return false;
-  }
   i::V8::TearDown();
   return true;
 }
@@ -4203,56 +5076,57 @@
 
 HeapStatistics::HeapStatistics(): total_heap_size_(0),
                                   total_heap_size_executable_(0),
+                                  total_physical_size_(0),
                                   used_heap_size_(0),
                                   heap_size_limit_(0) { }
 
 
-void v8::V8::GetHeapStatistics(HeapStatistics* heap_statistics) {
-  if (!i::Isolate::Current()->IsInitialized()) {
-    // Isolate is unitialized thus heap is not configured yet.
-    heap_statistics->set_total_heap_size(0);
-    heap_statistics->set_total_heap_size_executable(0);
-    heap_statistics->set_used_heap_size(0);
-    heap_statistics->set_heap_size_limit(0);
-    return;
-  }
-
-  i::Heap* heap = i::Isolate::Current()->heap();
-  heap_statistics->set_total_heap_size(heap->CommittedMemory());
-  heap_statistics->set_total_heap_size_executable(
-      heap->CommittedMemoryExecutable());
-  heap_statistics->set_used_heap_size(heap->SizeOfObjects());
-  heap_statistics->set_heap_size_limit(heap->MaxReserved());
-}
-
-
 void v8::V8::VisitExternalResources(ExternalResourceVisitor* visitor) {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::V8::VisitExternalResources");
   isolate->heap()->VisitExternalResources(visitor);
 }
 
 
-bool v8::V8::IdleNotification(int hint) {
-  // Returning true tells the caller that it need not
-  // continue to call IdleNotification.
+class VisitorAdapter : public i::ObjectVisitor {
+ public:
+  explicit VisitorAdapter(PersistentHandleVisitor* visitor)
+      : visitor_(visitor) {}
+  virtual void VisitPointers(i::Object** start, i::Object** end) {
+    UNREACHABLE();
+  }
+  virtual void VisitEmbedderReference(i::Object** p, uint16_t class_id) {
+    Value* value = ToApi<Value>(i::Handle<i::Object>(p));
+    visitor_->VisitPersistentHandle(
+        reinterpret_cast<Persistent<Value>*>(&value), class_id);
+  }
+ private:
+  PersistentHandleVisitor* visitor_;
+};
+
+
+void v8::V8::VisitHandlesWithClassIds(PersistentHandleVisitor* visitor) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (isolate == NULL || !isolate->IsInitialized()) return true;
-  return i::V8::IdleNotification(hint);
+  i::DisallowHeapAllocation no_allocation;
+
+  VisitorAdapter visitor_adapter(visitor);
+  isolate->global_handles()->IterateAllRootsWithClassIds(&visitor_adapter);
 }
 
 
-void v8::V8::LowMemoryNotification() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (isolate == NULL || !isolate->IsInitialized()) return;
-  isolate->heap()->CollectAllAvailableGarbage("low memory notification");
+void v8::V8::VisitHandlesForPartialDependence(
+    Isolate* exported_isolate, PersistentHandleVisitor* visitor) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(exported_isolate);
+  DCHECK(isolate == i::Isolate::Current());
+  i::DisallowHeapAllocation no_allocation;
+
+  VisitorAdapter visitor_adapter(visitor);
+  isolate->global_handles()->IterateAllRootsInNewSpaceWithClassIds(
+      &visitor_adapter);
 }
 
 
-int v8::V8::ContextDisposedNotification() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!isolate->IsInitialized()) return 0;
-  return isolate->heap()->NotifyContextDisposed();
+bool v8::V8::InitializeICU(const char* icu_data_file) {
+  return i::InitializeICU(icu_data_file);
 }
 
 
@@ -4261,30 +5135,14 @@
 }
 
 
-static i::Handle<i::FunctionTemplateInfo>
-    EnsureConstructor(i::Handle<i::ObjectTemplateInfo> templ) {
-  if (templ->constructor()->IsUndefined()) {
-    Local<FunctionTemplate> constructor = FunctionTemplate::New();
-    Utils::OpenHandle(*constructor)->set_instance_template(*templ);
-    templ->set_constructor(*Utils::OpenHandle(*constructor));
-  }
-  return i::Handle<i::FunctionTemplateInfo>(
-    i::FunctionTemplateInfo::cast(templ->constructor()));
-}
-
-
-Persistent<Context> v8::Context::New(
+static i::Handle<i::Context> CreateEnvironment(
+    i::Isolate* isolate,
     v8::ExtensionConfiguration* extensions,
     v8::Handle<ObjectTemplate> global_template,
-    v8::Handle<Value> global_object) {
-  i::Isolate::EnsureDefaultIsolate();
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Context::New()");
-  LOG_API(isolate, "Context::New");
-  ON_BAILOUT(isolate, "v8::Context::New()", return Persistent<Context>());
+    v8::Handle<Value> maybe_global_proxy) {
+  i::Handle<i::Context> env;
 
   // Enter V8 via an ENTER_V8 scope.
-  i::Handle<i::Context> env;
   {
     ENTER_V8(isolate);
     v8::Handle<ObjectTemplate> proxy_template = global_template;
@@ -4293,13 +5151,12 @@
 
     if (!global_template.IsEmpty()) {
       // Make sure that the global_template has a constructor.
-      global_constructor =
-          EnsureConstructor(Utils::OpenHandle(*global_template));
+      global_constructor = EnsureConstructor(isolate, *global_template);
 
       // Create a fresh template for the global proxy object.
-      proxy_template = ObjectTemplate::New();
-      proxy_constructor =
-          EnsureConstructor(Utils::OpenHandle(*proxy_template));
+      proxy_template = ObjectTemplate::New(
+          reinterpret_cast<v8::Isolate*>(isolate));
+      proxy_constructor = EnsureConstructor(isolate, *proxy_template);
 
       // Set the global template to be the prototype template of
       // global proxy template.
@@ -4320,38 +5177,50 @@
       }
     }
 
+    i::Handle<i::Object> proxy = Utils::OpenHandle(*maybe_global_proxy, true);
+    i::MaybeHandle<i::JSGlobalProxy> maybe_proxy;
+    if (!proxy.is_null()) {
+      maybe_proxy = i::Handle<i::JSGlobalProxy>::cast(proxy);
+    }
     // Create the environment.
     env = isolate->bootstrapper()->CreateEnvironment(
-        isolate,
-        Utils::OpenHandle(*global_object),
-        proxy_template,
-        extensions);
+        maybe_proxy, proxy_template, extensions);
 
     // Restore the access check info on the global template.
     if (!global_template.IsEmpty()) {
-      ASSERT(!global_constructor.is_null());
-      ASSERT(!proxy_constructor.is_null());
+      DCHECK(!global_constructor.is_null());
+      DCHECK(!proxy_constructor.is_null());
       global_constructor->set_access_check_info(
           proxy_constructor->access_check_info());
       global_constructor->set_needs_access_check(
           proxy_constructor->needs_access_check());
     }
-    isolate->runtime_profiler()->Reset();
   }
   // Leave V8.
 
-  if (env.is_null()) {
-    return Persistent<Context>();
-  }
-  return Persistent<Context>(Utils::ToLocal(env));
+  return env;
+}
+
+Local<Context> v8::Context::New(
+    v8::Isolate* external_isolate,
+    v8::ExtensionConfiguration* extensions,
+    v8::Handle<ObjectTemplate> global_template,
+    v8::Handle<Value> global_object) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(external_isolate);
+  LOG_API(isolate, "Context::New");
+  ON_BAILOUT(isolate, "v8::Context::New()", return Local<Context>());
+  i::HandleScope scope(isolate);
+  ExtensionConfiguration no_extensions;
+  if (extensions == NULL) extensions = &no_extensions;
+  i::Handle<i::Context> env =
+      CreateEnvironment(isolate, extensions, global_template, global_object);
+  if (env.is_null()) return Local<Context>();
+  return Utils::ToLocal(scope.CloseAndEscape(env));
 }
 
 
 void v8::Context::SetSecurityToken(Handle<Value> token) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::SetSecurityToken()")) {
-    return;
-  }
   ENTER_V8(isolate);
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Handle<i::Object> token_handle = Utils::OpenHandle(*token);
@@ -4361,143 +5230,69 @@
 
 void v8::Context::UseDefaultSecurityToken() {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate,
-                  "v8::Context::UseDefaultSecurityToken()")) {
-    return;
-  }
   ENTER_V8(isolate);
   i::Handle<i::Context> env = Utils::OpenHandle(this);
-  env->set_security_token(env->global());
+  env->set_security_token(env->global_object());
 }
 
 
 Handle<Value> v8::Context::GetSecurityToken() {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::GetSecurityToken()")) {
-    return Handle<Value>();
-  }
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Object* security_token = env->security_token();
-  i::Handle<i::Object> token_handle(security_token);
+  i::Handle<i::Object> token_handle(security_token, isolate);
   return Utils::ToLocal(token_handle);
 }
 
 
-bool Context::HasOutOfMemoryException() {
+v8::Isolate* Context::GetIsolate() {
   i::Handle<i::Context> env = Utils::OpenHandle(this);
-  return env->has_out_of_memory();
-}
-
-
-bool Context::InContext() {
-  return i::Isolate::Current()->context() != NULL;
-}
-
-
-v8::Local<v8::Context> Context::GetEntered() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!EnsureInitializedForIsolate(isolate, "v8::Context::GetEntered()")) {
-    return Local<Context>();
-  }
-  i::Handle<i::Object> last =
-      isolate->handle_scope_implementer()->LastEnteredContext();
-  if (last.is_null()) return Local<Context>();
-  i::Handle<i::Context> context = i::Handle<i::Context>::cast(last);
-  return Utils::ToLocal(context);
-}
-
-
-v8::Local<v8::Context> Context::GetCurrent() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::GetCurrent()")) {
-    return Local<Context>();
-  }
-  i::Handle<i::Object> current = isolate->global_context();
-  if (current.is_null()) return Local<Context>();
-  i::Handle<i::Context> context = i::Handle<i::Context>::cast(current);
-  return Utils::ToLocal(context);
-}
-
-
-v8::Local<v8::Context> Context::GetCalling() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::GetCalling()")) {
-    return Local<Context>();
-  }
-  i::Handle<i::Object> calling =
-      isolate->GetCallingGlobalContext();
-  if (calling.is_null()) return Local<Context>();
-  i::Handle<i::Context> context = i::Handle<i::Context>::cast(calling);
-  return Utils::ToLocal(context);
+  return reinterpret_cast<Isolate*>(env->GetIsolate());
 }
 
 
 v8::Local<v8::Object> Context::Global() {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::Context::Global()")) {
-    return Local<v8::Object>();
+  i::Handle<i::Context> context = Utils::OpenHandle(this);
+  i::Isolate* isolate = context->GetIsolate();
+  i::Handle<i::Object> global(context->global_proxy(), isolate);
+  // TODO(dcarney): This should always return the global proxy
+  // but can't presently as calls to GetProtoype will return the wrong result.
+  if (i::Handle<i::JSGlobalProxy>::cast(
+          global)->IsDetachedFrom(context->global_object())) {
+    global = i::Handle<i::Object>(context->global_object(), isolate);
   }
-  i::Object** ctx = reinterpret_cast<i::Object**>(this);
-  i::Handle<i::Context> context =
-      i::Handle<i::Context>::cast(i::Handle<i::Object>(ctx));
-  i::Handle<i::Object> global(context->global_proxy());
   return Utils::ToLocal(i::Handle<i::JSObject>::cast(global));
 }
 
 
 void Context::DetachGlobal() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::DetachGlobal()")) return;
+  i::Handle<i::Context> context = Utils::OpenHandle(this);
+  i::Isolate* isolate = context->GetIsolate();
   ENTER_V8(isolate);
-  i::Object** ctx = reinterpret_cast<i::Object**>(this);
-  i::Handle<i::Context> context =
-      i::Handle<i::Context>::cast(i::Handle<i::Object>(ctx));
   isolate->bootstrapper()->DetachGlobal(context);
 }
 
 
-void Context::ReattachGlobal(Handle<Object> global_object) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::ReattachGlobal()")) return;
-  ENTER_V8(isolate);
-  i::Object** ctx = reinterpret_cast<i::Object**>(this);
-  i::Handle<i::Context> context =
-      i::Handle<i::Context>::cast(i::Handle<i::Object>(ctx));
-  isolate->bootstrapper()->ReattachGlobal(
-      context,
-      Utils::OpenHandle(*global_object));
-}
-
-
 void Context::AllowCodeGenerationFromStrings(bool allow) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Context::AllowCodeGenerationFromStrings()")) {
-    return;
-  }
+  i::Handle<i::Context> context = Utils::OpenHandle(this);
+  i::Isolate* isolate = context->GetIsolate();
   ENTER_V8(isolate);
-  i::Object** ctx = reinterpret_cast<i::Object**>(this);
-  i::Handle<i::Context> context =
-      i::Handle<i::Context>::cast(i::Handle<i::Object>(ctx));
   context->set_allow_code_gen_from_strings(
       allow ? isolate->heap()->true_value() : isolate->heap()->false_value());
 }
 
 
 bool Context::IsCodeGenerationFromStringsAllowed() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate,
-                  "v8::Context::IsCodeGenerationFromStringsAllowed()")) {
-    return false;
-  }
-  ENTER_V8(isolate);
-  i::Object** ctx = reinterpret_cast<i::Object**>(this);
-  i::Handle<i::Context> context =
-      i::Handle<i::Context>::cast(i::Handle<i::Object>(ctx));
+  i::Handle<i::Context> context = Utils::OpenHandle(this);
   return !context->allow_code_gen_from_strings()->IsFalse();
 }
 
 
-void V8::SetWrapperClassId(i::Object** global_handle, uint16_t class_id) {
-  i::GlobalHandles::SetWrapperClassId(global_handle, class_id);
+void Context::SetErrorMessageForCodeGenerationFromStrings(
+    Handle<String> error) {
+  i::Handle<i::Context> context = Utils::OpenHandle(this);
+  i::Handle<i::String> error_handle = Utils::OpenHandle(*error);
+  context->set_error_message_for_code_gen_from_strings(*error_handle);
 }
 
 
@@ -4508,9 +5303,9 @@
   LOG_API(isolate, "ObjectTemplate::NewInstance");
   ENTER_V8(isolate);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj =
-      i::Execution::InstantiateObject(Utils::OpenHandle(this),
-                                      &has_pending_exception);
+  i::Handle<i::Object> obj;
+  has_pending_exception = !i::Execution::InstantiateObject(
+      Utils::OpenHandle(this)).ToHandle(&obj);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Object>());
   return Utils::ToLocal(i::Handle<i::JSObject>::cast(obj));
 }
@@ -4523,9 +5318,9 @@
   LOG_API(isolate, "FunctionTemplate::GetFunction");
   ENTER_V8(isolate);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj =
-      i::Execution::InstantiateFunction(Utils::OpenHandle(this),
-                                        &has_pending_exception);
+  i::Handle<i::Object> obj;
+  has_pending_exception = !i::Execution::InstantiateFunction(
+      Utils::OpenHandle(this)).ToHandle(&obj);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Function>());
   return Utils::ToLocal(i::Handle<i::JSFunction>::cast(obj));
 }
@@ -4535,189 +5330,186 @@
   ON_BAILOUT(i::Isolate::Current(), "v8::FunctionTemplate::HasInstanceOf()",
              return false);
   i::Object* obj = *Utils::OpenHandle(*value);
-  return obj->IsInstanceOf(*Utils::OpenHandle(this));
+  return Utils::OpenHandle(this)->IsTemplateFor(obj);
 }
 
 
-static Local<External> ExternalNewImpl(void* data) {
-  return Utils::ToLocal(FACTORY->NewForeign(static_cast<i::Address>(data)));
-}
-
-static void* ExternalValueImpl(i::Handle<i::Object> obj) {
-  return reinterpret_cast<void*>(i::Foreign::cast(*obj)->foreign_address());
-}
-
-
-Local<Value> v8::External::Wrap(void* data) {
-  i::Isolate* isolate = i::Isolate::Current();
-  STATIC_ASSERT(sizeof(data) == sizeof(i::Address));
-  EnsureInitializedForIsolate(isolate, "v8::External::Wrap()");
-  LOG_API(isolate, "External::Wrap");
-  ENTER_V8(isolate);
-
-  v8::Local<v8::Value> result = CanBeEncodedAsSmi(data)
-      ? Utils::ToLocal(i::Handle<i::Object>(EncodeAsSmi(data)))
-      : v8::Local<v8::Value>(ExternalNewImpl(data));
-
-  ASSERT_EQ(data, Unwrap(result));
-  return result;
-}
-
-
-void* v8::Object::SlowGetPointerFromInternalField(int index) {
-  i::Handle<i::JSObject> obj = Utils::OpenHandle(this);
-  i::Object* value = obj->GetInternalField(index);
-  if (value->IsSmi()) {
-    return i::Internals::GetExternalPointerFromSmi(value);
-  } else if (value->IsForeign()) {
-    return reinterpret_cast<void*>(i::Foreign::cast(value)->foreign_address());
-  } else {
-    return NULL;
-  }
-}
-
-
-void* v8::External::FullUnwrap(v8::Handle<v8::Value> wrapper) {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::External::Unwrap()")) return 0;
-  i::Handle<i::Object> obj = Utils::OpenHandle(*wrapper);
-  void* result;
-  if (obj->IsSmi()) {
-    result = i::Internals::GetExternalPointerFromSmi(*obj);
-  } else if (obj->IsForeign()) {
-    result = ExternalValueImpl(obj);
-  } else {
-    result = NULL;
-  }
-  ASSERT_EQ(result, QuickUnwrap(wrapper));
-  return result;
-}
-
-
-Local<External> v8::External::New(void* data) {
-  STATIC_ASSERT(sizeof(data) == sizeof(i::Address));
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::External::New()");
-  LOG_API(isolate, "External::New");
-  ENTER_V8(isolate);
-  return ExternalNewImpl(data);
+Local<External> v8::External::New(Isolate* isolate, void* value) {
+  STATIC_ASSERT(sizeof(value) == sizeof(i::Address));
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "External::New");
+  ENTER_V8(i_isolate);
+  i::Handle<i::JSObject> external = i_isolate->factory()->NewExternal(value);
+  return Utils::ExternalToLocal(external);
 }
 
 
 void* External::Value() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::External::Value()")) return 0;
-  i::Handle<i::Object> obj = Utils::OpenHandle(this);
-  return ExternalValueImpl(obj);
+  return ExternalValue(*Utils::OpenHandle(this));
 }
 
 
-Local<String> v8::String::Empty() {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::Empty()");
-  LOG_API(isolate, "String::Empty()");
-  return Utils::ToLocal(isolate->factory()->empty_symbol());
+// anonymous namespace for string creation helper functions
+namespace {
+
+inline int StringLength(const char* string) {
+  return i::StrLength(string);
 }
 
 
-Local<String> v8::String::New(const char* data, int length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::New()");
-  LOG_API(isolate, "String::New(char)");
-  if (length == 0) return Empty();
+inline int StringLength(const uint8_t* string) {
+  return i::StrLength(reinterpret_cast<const char*>(string));
+}
+
+
+inline int StringLength(const uint16_t* string) {
+  int length = 0;
+  while (string[length] != '\0')
+    length++;
+  return length;
+}
+
+
+MUST_USE_RESULT
+inline i::MaybeHandle<i::String> NewString(i::Factory* factory,
+                                           String::NewStringType type,
+                                           i::Vector<const char> string) {
+  if (type == String::kInternalizedString) {
+    return factory->InternalizeUtf8String(string);
+  }
+  return factory->NewStringFromUtf8(string);
+}
+
+
+MUST_USE_RESULT
+inline i::MaybeHandle<i::String> NewString(i::Factory* factory,
+                                           String::NewStringType type,
+                                           i::Vector<const uint8_t> string) {
+  if (type == String::kInternalizedString) {
+    return factory->InternalizeOneByteString(string);
+  }
+  return factory->NewStringFromOneByte(string);
+}
+
+
+MUST_USE_RESULT
+inline i::MaybeHandle<i::String> NewString(i::Factory* factory,
+                                           String::NewStringType type,
+                                           i::Vector<const uint16_t> string) {
+  if (type == String::kInternalizedString) {
+    return factory->InternalizeTwoByteString(string);
+  }
+  return factory->NewStringFromTwoByte(string);
+}
+
+
+template<typename Char>
+inline Local<String> NewString(Isolate* v8_isolate,
+                               const char* location,
+                               const char* env,
+                               const Char* data,
+                               String::NewStringType type,
+                               int length) {
+  i::Isolate* isolate = reinterpret_cast<internal::Isolate*>(v8_isolate);
+  LOG_API(isolate, env);
+  if (length == 0 && type != String::kUndetectableString) {
+    return String::Empty(v8_isolate);
+  }
   ENTER_V8(isolate);
-  if (length == -1) length = i::StrLength(data);
-  i::Handle<i::String> result =
-      isolate->factory()->NewStringFromUtf8(
-          i::Vector<const char>(data, length));
+  if (length == -1) length = StringLength(data);
+  // We do not expect this to fail. Change this if it does.
+  i::Handle<i::String> result = NewString(
+      isolate->factory(),
+      type,
+      i::Vector<const Char>(data, length)).ToHandleChecked();
+  if (type == String::kUndetectableString) {
+    result->MarkAsUndetectable();
+  }
   return Utils::ToLocal(result);
 }
 
+}  // anonymous namespace
+
+
+Local<String> String::NewFromUtf8(Isolate* isolate,
+                                  const char* data,
+                                  NewStringType type,
+                                  int length) {
+  return NewString(isolate,
+                   "v8::String::NewFromUtf8()",
+                   "String::NewFromUtf8",
+                   data,
+                   type,
+                   length);
+}
+
+
+Local<String> String::NewFromOneByte(Isolate* isolate,
+                                     const uint8_t* data,
+                                     NewStringType type,
+                                     int length) {
+  return NewString(isolate,
+                   "v8::String::NewFromOneByte()",
+                   "String::NewFromOneByte",
+                   data,
+                   type,
+                   length);
+}
+
+
+Local<String> String::NewFromTwoByte(Isolate* isolate,
+                                     const uint16_t* data,
+                                     NewStringType type,
+                                     int length) {
+  return NewString(isolate,
+                   "v8::String::NewFromTwoByte()",
+                   "String::NewFromTwoByte",
+                   data,
+                   type,
+                   length);
+}
+
 
 Local<String> v8::String::Concat(Handle<String> left, Handle<String> right) {
   i::Handle<i::String> left_string = Utils::OpenHandle(*left);
   i::Isolate* isolate = left_string->GetIsolate();
-  EnsureInitializedForIsolate(isolate, "v8::String::New()");
   LOG_API(isolate, "String::New(char)");
   ENTER_V8(isolate);
   i::Handle<i::String> right_string = Utils::OpenHandle(*right);
-  i::Handle<i::String> result = isolate->factory()->NewConsString(left_string,
-                                                                  right_string);
+  // We do not expect this to fail. Change this if it does.
+  i::Handle<i::String> result = isolate->factory()->NewConsString(
+      left_string, right_string).ToHandleChecked();
   return Utils::ToLocal(result);
 }
 
 
-Local<String> v8::String::NewUndetectable(const char* data, int length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::NewUndetectable()");
-  LOG_API(isolate, "String::NewUndetectable(char)");
-  ENTER_V8(isolate);
-  if (length == -1) length = i::StrLength(data);
-  i::Handle<i::String> result =
-      isolate->factory()->NewStringFromUtf8(
-          i::Vector<const char>(data, length));
-  result->MarkAsUndetectable();
-  return Utils::ToLocal(result);
+static i::Handle<i::String> NewExternalStringHandle(
+    i::Isolate* isolate,
+    v8::String::ExternalStringResource* resource) {
+  // We do not expect this to fail. Change this if it does.
+  return isolate->factory()->NewExternalStringFromTwoByte(
+      resource).ToHandleChecked();
 }
 
 
-static int TwoByteStringLength(const uint16_t* data) {
-  int length = 0;
-  while (data[length] != '\0') length++;
-  return length;
-}
-
-
-Local<String> v8::String::New(const uint16_t* data, int length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::New()");
-  LOG_API(isolate, "String::New(uint16_)");
-  if (length == 0) return Empty();
-  ENTER_V8(isolate);
-  if (length == -1) length = TwoByteStringLength(data);
-  i::Handle<i::String> result =
-      isolate->factory()->NewStringFromTwoByte(
-          i::Vector<const uint16_t>(data, length));
-  return Utils::ToLocal(result);
-}
-
-
-Local<String> v8::String::NewUndetectable(const uint16_t* data, int length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::NewUndetectable()");
-  LOG_API(isolate, "String::NewUndetectable(uint16_)");
-  ENTER_V8(isolate);
-  if (length == -1) length = TwoByteStringLength(data);
-  i::Handle<i::String> result =
-      isolate->factory()->NewStringFromTwoByte(
-          i::Vector<const uint16_t>(data, length));
-  result->MarkAsUndetectable();
-  return Utils::ToLocal(result);
-}
-
-
-i::Handle<i::String> NewExternalStringHandle(i::Isolate* isolate,
-      v8::String::ExternalStringResource* resource) {
-  i::Handle<i::String> result =
-      isolate->factory()->NewExternalStringFromTwoByte(resource);
-  return result;
-}
-
-
-i::Handle<i::String> NewExternalAsciiStringHandle(i::Isolate* isolate,
-      v8::String::ExternalAsciiStringResource* resource) {
-  i::Handle<i::String> result =
-      isolate->factory()->NewExternalStringFromAscii(resource);
-  return result;
+static i::Handle<i::String> NewExternalOneByteStringHandle(
+    i::Isolate* isolate, v8::String::ExternalOneByteStringResource* resource) {
+  // We do not expect this to fail. Change this if it does.
+  return isolate->factory()
+      ->NewExternalStringFromOneByte(resource)
+      .ToHandleChecked();
 }
 
 
 Local<String> v8::String::NewExternal(
-      v8::String::ExternalStringResource* resource) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::NewExternal()");
-  LOG_API(isolate, "String::NewExternal");
-  ENTER_V8(isolate);
-  i::Handle<i::String> result = NewExternalStringHandle(isolate, resource);
-  isolate->heap()->external_string_table()->AddString(*result);
+    Isolate* isolate,
+    v8::String::ExternalStringResource* resource) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "String::NewExternal");
+  ENTER_V8(i_isolate);
+  CHECK(resource && resource->data());
+  i::Handle<i::String> result = NewExternalStringHandle(i_isolate, resource);
+  i_isolate->heap()->external_string_table()->AddString(*result);
   return Utils::ToLocal(result);
 }
 
@@ -4725,8 +5517,7 @@
 bool v8::String::MakeExternal(v8::String::ExternalStringResource* resource) {
   i::Handle<i::String> obj = Utils::OpenHandle(this);
   i::Isolate* isolate = obj->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::String::MakeExternal()")) return false;
-  if (i::StringShape(*obj).IsExternalTwoByte()) {
+  if (i::StringShape(*obj).IsExternal()) {
     return false;  // Already an external string.
   }
   ENTER_V8(isolate);
@@ -4736,8 +5527,13 @@
   if (isolate->heap()->IsInGCPostProcessing()) {
     return false;
   }
+  CHECK(resource && resource->data());
+
   bool result = obj->MakeExternal(resource);
-  if (result && !obj->IsSymbol()) {
+  // Assert that if CanMakeExternal(), then externalizing actually succeeds.
+  DCHECK(!CanMakeExternal() || result);
+  if (result) {
+    DCHECK(obj->IsExternalString());
     isolate->heap()->external_string_table()->AddString(*obj);
   }
   return result;
@@ -4745,23 +5541,23 @@
 
 
 Local<String> v8::String::NewExternal(
-      v8::String::ExternalAsciiStringResource* resource) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::NewExternal()");
-  LOG_API(isolate, "String::NewExternal");
-  ENTER_V8(isolate);
-  i::Handle<i::String> result = NewExternalAsciiStringHandle(isolate, resource);
-  isolate->heap()->external_string_table()->AddString(*result);
+    Isolate* isolate, v8::String::ExternalOneByteStringResource* resource) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "String::NewExternal");
+  ENTER_V8(i_isolate);
+  CHECK(resource && resource->data());
+  i::Handle<i::String> result =
+      NewExternalOneByteStringHandle(i_isolate, resource);
+  i_isolate->heap()->external_string_table()->AddString(*result);
   return Utils::ToLocal(result);
 }
 
 
 bool v8::String::MakeExternal(
-    v8::String::ExternalAsciiStringResource* resource) {
+    v8::String::ExternalOneByteStringResource* resource) {
   i::Handle<i::String> obj = Utils::OpenHandle(this);
   i::Isolate* isolate = obj->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::String::MakeExternal()")) return false;
-  if (i::StringShape(*obj).IsExternalTwoByte()) {
+  if (i::StringShape(*obj).IsExternal()) {
     return false;  // Already an external string.
   }
   ENTER_V8(isolate);
@@ -4771,8 +5567,13 @@
   if (isolate->heap()->IsInGCPostProcessing()) {
     return false;
   }
+  CHECK(resource && resource->data());
+
   bool result = obj->MakeExternal(resource);
-  if (result && !obj->IsSymbol()) {
+  // Assert that if CanMakeExternal(), then externalizing actually succeeds.
+  DCHECK(!CanMakeExternal() || result);
+  if (result) {
+    DCHECK(obj->IsExternalString());
     isolate->heap()->external_string_table()->AddString(*obj);
   }
   return result;
@@ -4783,7 +5584,7 @@
   if (!internal::FLAG_clever_optimizations) return false;
   i::Handle<i::String> obj = Utils::OpenHandle(this);
   i::Isolate* isolate = obj->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::String::CanMakeExternal()")) return false;
+
   if (isolate->string_tracker()->IsFreshUnusedString(obj)) return false;
   int size = obj->Size();  // Byte size of the original string.
   if (size < i::ExternalString::kShortSize) return false;
@@ -4792,187 +5593,188 @@
 }
 
 
-Local<v8::Object> v8::Object::New() {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Object::New()");
-  LOG_API(isolate, "Object::New");
-  ENTER_V8(isolate);
+Local<v8::Object> v8::Object::New(Isolate* isolate) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "Object::New");
+  ENTER_V8(i_isolate);
   i::Handle<i::JSObject> obj =
-      isolate->factory()->NewJSObject(isolate->object_function());
+      i_isolate->factory()->NewJSObject(i_isolate->object_function());
   return Utils::ToLocal(obj);
 }
 
 
-Local<v8::Value> v8::NumberObject::New(double value) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::NumberObject::New()");
-  LOG_API(isolate, "NumberObject::New");
-  ENTER_V8(isolate);
-  i::Handle<i::Object> number = isolate->factory()->NewNumber(value);
-  i::Handle<i::Object> obj = isolate->factory()->ToObject(number);
+Local<v8::Value> v8::NumberObject::New(Isolate* isolate, double value) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "NumberObject::New");
+  ENTER_V8(i_isolate);
+  i::Handle<i::Object> number = i_isolate->factory()->NewNumber(value);
+  i::Handle<i::Object> obj =
+      i::Object::ToObject(i_isolate, number).ToHandleChecked();
   return Utils::ToLocal(obj);
 }
 
 
-double v8::NumberObject::NumberValue() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::NumberObject::NumberValue()")) return 0;
-  LOG_API(isolate, "NumberObject::NumberValue");
+double v8::NumberObject::ValueOf() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   i::Handle<i::JSValue> jsvalue = i::Handle<i::JSValue>::cast(obj);
+  i::Isolate* isolate = jsvalue->GetIsolate();
+  LOG_API(isolate, "NumberObject::NumberValue");
   return jsvalue->value()->Number();
 }
 
 
 Local<v8::Value> v8::BooleanObject::New(bool value) {
   i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::BooleanObject::New()");
   LOG_API(isolate, "BooleanObject::New");
   ENTER_V8(isolate);
-  i::Handle<i::Object> boolean(value ? isolate->heap()->true_value()
-                                     : isolate->heap()->false_value());
-  i::Handle<i::Object> obj = isolate->factory()->ToObject(boolean);
+  i::Handle<i::Object> boolean(value
+                               ? isolate->heap()->true_value()
+                               : isolate->heap()->false_value(),
+                               isolate);
+  i::Handle<i::Object> obj =
+      i::Object::ToObject(isolate, boolean).ToHandleChecked();
   return Utils::ToLocal(obj);
 }
 
 
-bool v8::BooleanObject::BooleanValue() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::BooleanObject::BooleanValue()")) return 0;
-  LOG_API(isolate, "BooleanObject::BooleanValue");
+bool v8::BooleanObject::ValueOf() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   i::Handle<i::JSValue> jsvalue = i::Handle<i::JSValue>::cast(obj);
+  i::Isolate* isolate = jsvalue->GetIsolate();
+  LOG_API(isolate, "BooleanObject::BooleanValue");
   return jsvalue->value()->IsTrue();
 }
 
 
 Local<v8::Value> v8::StringObject::New(Handle<String> value) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::StringObject::New()");
+  i::Handle<i::String> string = Utils::OpenHandle(*value);
+  i::Isolate* isolate = string->GetIsolate();
   LOG_API(isolate, "StringObject::New");
   ENTER_V8(isolate);
   i::Handle<i::Object> obj =
-      isolate->factory()->ToObject(Utils::OpenHandle(*value));
+      i::Object::ToObject(isolate, string).ToHandleChecked();
   return Utils::ToLocal(obj);
 }
 
 
-Local<v8::String> v8::StringObject::StringValue() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::StringObject::StringValue()")) {
-    return Local<v8::String>();
-  }
-  LOG_API(isolate, "StringObject::StringValue");
+Local<v8::String> v8::StringObject::ValueOf() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   i::Handle<i::JSValue> jsvalue = i::Handle<i::JSValue>::cast(obj);
+  i::Isolate* isolate = jsvalue->GetIsolate();
+  LOG_API(isolate, "StringObject::StringValue");
   return Utils::ToLocal(
       i::Handle<i::String>(i::String::cast(jsvalue->value())));
 }
 
 
-Local<v8::Value> v8::Date::New(double time) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Date::New()");
-  LOG_API(isolate, "Date::New");
-  if (isnan(time)) {
-    // Introduce only canonical NaN value into the VM, to avoid signaling NaNs.
-    time = i::OS::nan_value();
-  }
-  ENTER_V8(isolate);
-  EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::Object> obj =
-      i::Execution::NewDate(time, &has_pending_exception);
-  EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::Value>());
+Local<v8::Value> v8::SymbolObject::New(Isolate* isolate, Handle<Symbol> value) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "SymbolObject::New");
+  ENTER_V8(i_isolate);
+  i::Handle<i::Object> obj = i::Object::ToObject(
+      i_isolate, Utils::OpenHandle(*value)).ToHandleChecked();
   return Utils::ToLocal(obj);
 }
 
 
-double v8::Date::NumberValue() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::Date::NumberValue()")) return 0;
-  LOG_API(isolate, "Date::NumberValue");
+Local<v8::Symbol> v8::SymbolObject::ValueOf() const {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this);
+  i::Handle<i::JSValue> jsvalue = i::Handle<i::JSValue>::cast(obj);
+  i::Isolate* isolate = jsvalue->GetIsolate();
+  LOG_API(isolate, "SymbolObject::SymbolValue");
+  return Utils::ToLocal(
+      i::Handle<i::Symbol>(i::Symbol::cast(jsvalue->value())));
+}
+
+
+Local<v8::Value> v8::Date::New(Isolate* isolate, double time) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "Date::New");
+  if (std::isnan(time)) {
+    // Introduce only canonical NaN value into the VM, to avoid signaling NaNs.
+    time = base::OS::nan_value();
+  }
+  ENTER_V8(i_isolate);
+  EXCEPTION_PREAMBLE(i_isolate);
+  i::Handle<i::Object> obj;
+  has_pending_exception = !i::Execution::NewDate(
+      i_isolate, time).ToHandle(&obj);
+  EXCEPTION_BAILOUT_CHECK(i_isolate, Local<v8::Value>());
+  return Utils::ToLocal(obj);
+}
+
+
+double v8::Date::ValueOf() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   i::Handle<i::JSDate> jsdate = i::Handle<i::JSDate>::cast(obj);
+  i::Isolate* isolate = jsdate->GetIsolate();
+  LOG_API(isolate, "Date::NumberValue");
   return jsdate->value()->Number();
 }
 
 
-void v8::Date::DateTimeConfigurationChangeNotification() {
-  i::Isolate* isolate = i::Isolate::Current();
-  ON_BAILOUT(isolate, "v8::Date::DateTimeConfigurationChangeNotification()",
+void v8::Date::DateTimeConfigurationChangeNotification(Isolate* isolate) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  if (!i_isolate->IsInitialized()) return;
+  ON_BAILOUT(i_isolate, "v8::Date::DateTimeConfigurationChangeNotification()",
              return);
-  LOG_API(isolate, "Date::DateTimeConfigurationChangeNotification");
-  ENTER_V8(isolate);
+  LOG_API(i_isolate, "Date::DateTimeConfigurationChangeNotification");
+  ENTER_V8(i_isolate);
 
-  isolate->date_cache()->ResetDateCache();
+  i_isolate->date_cache()->ResetDateCache();
 
-  i::HandleScope scope(isolate);
-  // Get the function ResetDateCache (defined in date.js).
-  i::Handle<i::String> func_name_str =
-      isolate->factory()->LookupAsciiSymbol("ResetDateCache");
-  i::MaybeObject* result =
-      isolate->js_builtins_object()->GetProperty(*func_name_str);
-  i::Object* object_func;
-  if (!result->ToObject(&object_func)) {
+  if (!i_isolate->eternal_handles()->Exists(
+          i::EternalHandles::DATE_CACHE_VERSION)) {
     return;
   }
-
-  if (object_func->IsJSFunction()) {
-    i::Handle<i::JSFunction> func =
-        i::Handle<i::JSFunction>(i::JSFunction::cast(object_func));
-
-    // Call ResetDateCache(0 but expect no exceptions:
-    bool caught_exception = false;
-    i::Execution::TryCall(func,
-                          isolate->js_builtins_object(),
-                          0,
-                          NULL,
-                          &caught_exception);
-  }
+  i::Handle<i::FixedArray> date_cache_version =
+      i::Handle<i::FixedArray>::cast(i_isolate->eternal_handles()->GetSingleton(
+          i::EternalHandles::DATE_CACHE_VERSION));
+  DCHECK_EQ(1, date_cache_version->length());
+  CHECK(date_cache_version->get(0)->IsSmi());
+  date_cache_version->set(
+      0,
+      i::Smi::FromInt(i::Smi::cast(date_cache_version->get(0))->value() + 1));
 }
 
 
 static i::Handle<i::String> RegExpFlagsToString(RegExp::Flags flags) {
-  char flags_buf[3];
+  i::Isolate* isolate = i::Isolate::Current();
+  uint8_t flags_buf[3];
   int num_flags = 0;
   if ((flags & RegExp::kGlobal) != 0) flags_buf[num_flags++] = 'g';
   if ((flags & RegExp::kMultiline) != 0) flags_buf[num_flags++] = 'm';
   if ((flags & RegExp::kIgnoreCase) != 0) flags_buf[num_flags++] = 'i';
-  ASSERT(num_flags <= static_cast<int>(ARRAY_SIZE(flags_buf)));
-  return FACTORY->LookupSymbol(
-      i::Vector<const char>(flags_buf, num_flags));
+  DCHECK(num_flags <= static_cast<int>(arraysize(flags_buf)));
+  return isolate->factory()->InternalizeOneByteString(
+      i::Vector<const uint8_t>(flags_buf, num_flags));
 }
 
 
 Local<v8::RegExp> v8::RegExp::New(Handle<String> pattern,
                                   Flags flags) {
   i::Isolate* isolate = Utils::OpenHandle(*pattern)->GetIsolate();
-  EnsureInitializedForIsolate(isolate, "v8::RegExp::New()");
   LOG_API(isolate, "RegExp::New");
   ENTER_V8(isolate);
   EXCEPTION_PREAMBLE(isolate);
-  i::Handle<i::JSRegExp> obj = i::Execution::NewJSRegExp(
+  i::Handle<i::JSRegExp> obj;
+  has_pending_exception = !i::Execution::NewJSRegExp(
       Utils::OpenHandle(*pattern),
-      RegExpFlagsToString(flags),
-      &has_pending_exception);
+      RegExpFlagsToString(flags)).ToHandle(&obj);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<v8::RegExp>());
   return Utils::ToLocal(i::Handle<i::JSRegExp>::cast(obj));
 }
 
 
 Local<v8::String> v8::RegExp::GetSource() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::RegExp::GetSource()")) {
-    return Local<v8::String>();
-  }
   i::Handle<i::JSRegExp> obj = Utils::OpenHandle(this);
   return Utils::ToLocal(i::Handle<i::String>(obj->Pattern()));
 }
 
 
 // Assert that the static flags cast in GetFlags is valid.
-#define REGEXP_FLAG_ASSERT_EQ(api_flag, internal_flag)        \
-  STATIC_ASSERT(static_cast<int>(v8::RegExp::api_flag) ==     \
+#define REGEXP_FLAG_ASSERT_EQ(api_flag, internal_flag)          \
+  STATIC_ASSERT(static_cast<int>(v8::RegExp::api_flag) ==       \
                 static_cast<int>(i::JSRegExp::internal_flag))
 REGEXP_FLAG_ASSERT_EQ(kNone, NONE);
 REGEXP_FLAG_ASSERT_EQ(kGlobal, GLOBAL);
@@ -4981,31 +5783,25 @@
 #undef REGEXP_FLAG_ASSERT_EQ
 
 v8::RegExp::Flags v8::RegExp::GetFlags() const {
-  if (IsDeadCheck(i::Isolate::Current(), "v8::RegExp::GetFlags()")) {
-    return v8::RegExp::kNone;
-  }
   i::Handle<i::JSRegExp> obj = Utils::OpenHandle(this);
   return static_cast<RegExp::Flags>(obj->GetFlags().value());
 }
 
 
-Local<v8::Array> v8::Array::New(int length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Array::New()");
-  LOG_API(isolate, "Array::New");
-  ENTER_V8(isolate);
+Local<v8::Array> v8::Array::New(Isolate* isolate, int length) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "Array::New");
+  ENTER_V8(i_isolate);
   int real_length = length > 0 ? length : 0;
-  i::Handle<i::JSArray> obj = isolate->factory()->NewJSArray(real_length);
+  i::Handle<i::JSArray> obj = i_isolate->factory()->NewJSArray(real_length);
   i::Handle<i::Object> length_obj =
-      isolate->factory()->NewNumberFromInt(real_length);
+      i_isolate->factory()->NewNumberFromInt(real_length);
   obj->set_length(*length_obj);
   return Utils::ToLocal(obj);
 }
 
 
 uint32_t v8::Array::Length() const {
-  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
-  if (IsDeadCheck(isolate, "v8::Array::Length()")) return 0;
   i::Handle<i::JSArray> obj = Utils::OpenHandle(this);
   i::Object* length = obj->length();
   if (length->IsSmi()) {
@@ -5020,7 +5816,7 @@
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Array::CloneElementAt()", return Local<Object>());
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  if (!self->HasFastElements()) {
+  if (!self->HasFastObjectElements()) {
     return Local<Object>();
   }
   i::FixedArray* elms = i::FixedArray::cast(self->elements());
@@ -5031,80 +5827,479 @@
   i::Handle<i::JSObject> paragon_handle(i::JSObject::cast(paragon));
   EXCEPTION_PREAMBLE(isolate);
   ENTER_V8(isolate);
-  i::Handle<i::JSObject> result = i::Copy(paragon_handle);
+  i::Handle<i::JSObject> result =
+      isolate->factory()->CopyJSObject(paragon_handle);
   has_pending_exception = result.is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Object>());
   return Utils::ToLocal(result);
 }
 
 
-Local<String> v8::String::NewSymbol(const char* data, int length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::String::NewSymbol()");
-  LOG_API(isolate, "String::NewSymbol(char)");
+bool Value::IsPromise() const {
+  i::Handle<i::Object> val = Utils::OpenHandle(this);
+  if (!val->IsJSObject()) return false;
+  i::Handle<i::JSObject> obj = i::Handle<i::JSObject>::cast(val);
+  i::Isolate* isolate = obj->GetIsolate();
+  LOG_API(isolate, "IsPromise");
   ENTER_V8(isolate);
-  if (length == -1) length = i::StrLength(data);
-  i::Handle<i::String> result =
-      isolate->factory()->LookupSymbol(i::Vector<const char>(data, length));
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> argv[] = { obj };
+  i::Handle<i::Object> b;
+  has_pending_exception = !i::Execution::Call(
+      isolate,
+      isolate->is_promise(),
+      isolate->factory()->undefined_value(),
+      arraysize(argv), argv,
+      false).ToHandle(&b);
+  EXCEPTION_BAILOUT_CHECK(isolate, false);
+  return b->BooleanValue();
+}
+
+
+Local<Promise::Resolver> Promise::Resolver::New(Isolate* v8_isolate) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  LOG_API(isolate, "Promise::Resolver::New");
+  ENTER_V8(isolate);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> result;
+  has_pending_exception = !i::Execution::Call(
+      isolate,
+      isolate->promise_create(),
+      isolate->factory()->undefined_value(),
+      0, NULL,
+      false).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<Promise::Resolver>());
+  return Local<Promise::Resolver>::Cast(Utils::ToLocal(result));
+}
+
+
+Local<Promise> Promise::Resolver::GetPromise() {
+  i::Handle<i::JSObject> promise = Utils::OpenHandle(this);
+  return Local<Promise>::Cast(Utils::ToLocal(promise));
+}
+
+
+void Promise::Resolver::Resolve(Handle<Value> value) {
+  i::Handle<i::JSObject> promise = Utils::OpenHandle(this);
+  i::Isolate* isolate = promise->GetIsolate();
+  LOG_API(isolate, "Promise::Resolver::Resolve");
+  ENTER_V8(isolate);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> argv[] = { promise, Utils::OpenHandle(*value) };
+  has_pending_exception = i::Execution::Call(
+      isolate,
+      isolate->promise_resolve(),
+      isolate->factory()->undefined_value(),
+      arraysize(argv), argv,
+      false).is_null();
+  EXCEPTION_BAILOUT_CHECK(isolate, /* void */ ;);
+}
+
+
+void Promise::Resolver::Reject(Handle<Value> value) {
+  i::Handle<i::JSObject> promise = Utils::OpenHandle(this);
+  i::Isolate* isolate = promise->GetIsolate();
+  LOG_API(isolate, "Promise::Resolver::Reject");
+  ENTER_V8(isolate);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> argv[] = { promise, Utils::OpenHandle(*value) };
+  has_pending_exception = i::Execution::Call(
+      isolate,
+      isolate->promise_reject(),
+      isolate->factory()->undefined_value(),
+      arraysize(argv), argv,
+      false).is_null();
+  EXCEPTION_BAILOUT_CHECK(isolate, /* void */ ;);
+}
+
+
+Local<Promise> Promise::Chain(Handle<Function> handler) {
+  i::Handle<i::JSObject> promise = Utils::OpenHandle(this);
+  i::Isolate* isolate = promise->GetIsolate();
+  LOG_API(isolate, "Promise::Chain");
+  ENTER_V8(isolate);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> argv[] = { Utils::OpenHandle(*handler) };
+  i::Handle<i::Object> result;
+  has_pending_exception = !i::Execution::Call(
+      isolate,
+      isolate->promise_chain(),
+      promise,
+      arraysize(argv), argv,
+      false).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<Promise>());
+  return Local<Promise>::Cast(Utils::ToLocal(result));
+}
+
+
+Local<Promise> Promise::Catch(Handle<Function> handler) {
+  i::Handle<i::JSObject> promise = Utils::OpenHandle(this);
+  i::Isolate* isolate = promise->GetIsolate();
+  LOG_API(isolate, "Promise::Catch");
+  ENTER_V8(isolate);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> argv[] = { Utils::OpenHandle(*handler) };
+  i::Handle<i::Object> result;
+  has_pending_exception = !i::Execution::Call(
+      isolate,
+      isolate->promise_catch(),
+      promise,
+      arraysize(argv), argv,
+      false).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<Promise>());
+  return Local<Promise>::Cast(Utils::ToLocal(result));
+}
+
+
+Local<Promise> Promise::Then(Handle<Function> handler) {
+  i::Handle<i::JSObject> promise = Utils::OpenHandle(this);
+  i::Isolate* isolate = promise->GetIsolate();
+  LOG_API(isolate, "Promise::Then");
+  ENTER_V8(isolate);
+  EXCEPTION_PREAMBLE(isolate);
+  i::Handle<i::Object> argv[] = { Utils::OpenHandle(*handler) };
+  i::Handle<i::Object> result;
+  has_pending_exception = !i::Execution::Call(
+      isolate,
+      isolate->promise_then(),
+      promise,
+      arraysize(argv), argv,
+      false).ToHandle(&result);
+  EXCEPTION_BAILOUT_CHECK(isolate, Local<Promise>());
+  return Local<Promise>::Cast(Utils::ToLocal(result));
+}
+
+
+bool v8::ArrayBuffer::IsExternal() const {
+  return Utils::OpenHandle(this)->is_external();
+}
+
+
+v8::ArrayBuffer::Contents v8::ArrayBuffer::Externalize() {
+  i::Handle<i::JSArrayBuffer> obj = Utils::OpenHandle(this);
+  Utils::ApiCheck(!obj->is_external(),
+                  "v8::ArrayBuffer::Externalize",
+                  "ArrayBuffer already externalized");
+  obj->set_is_external(true);
+  size_t byte_length = static_cast<size_t>(obj->byte_length()->Number());
+  Contents contents;
+  contents.data_ = obj->backing_store();
+  contents.byte_length_ = byte_length;
+  return contents;
+}
+
+
+void v8::ArrayBuffer::Neuter() {
+  i::Handle<i::JSArrayBuffer> obj = Utils::OpenHandle(this);
+  i::Isolate* isolate = obj->GetIsolate();
+  Utils::ApiCheck(obj->is_external(),
+                  "v8::ArrayBuffer::Neuter",
+                  "Only externalized ArrayBuffers can be neutered");
+  LOG_API(obj->GetIsolate(), "v8::ArrayBuffer::Neuter()");
+  ENTER_V8(isolate);
+  i::Runtime::NeuterArrayBuffer(obj);
+}
+
+
+size_t v8::ArrayBuffer::ByteLength() const {
+  i::Handle<i::JSArrayBuffer> obj = Utils::OpenHandle(this);
+  return static_cast<size_t>(obj->byte_length()->Number());
+}
+
+
+Local<ArrayBuffer> v8::ArrayBuffer::New(Isolate* isolate, size_t byte_length) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "v8::ArrayBuffer::New(size_t)");
+  ENTER_V8(i_isolate);
+  i::Handle<i::JSArrayBuffer> obj =
+      i_isolate->factory()->NewJSArrayBuffer();
+  i::Runtime::SetupArrayBufferAllocatingData(i_isolate, obj, byte_length);
+  return Utils::ToLocal(obj);
+}
+
+
+Local<ArrayBuffer> v8::ArrayBuffer::New(Isolate* isolate, void* data,
+                                        size_t byte_length) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "v8::ArrayBuffer::New(void*, size_t)");
+  ENTER_V8(i_isolate);
+  i::Handle<i::JSArrayBuffer> obj =
+      i_isolate->factory()->NewJSArrayBuffer();
+  i::Runtime::SetupArrayBuffer(i_isolate, obj, true, data, byte_length);
+  return Utils::ToLocal(obj);
+}
+
+
+Local<ArrayBuffer> v8::ArrayBufferView::Buffer() {
+  i::Handle<i::JSArrayBufferView> obj = Utils::OpenHandle(this);
+  i::Handle<i::JSArrayBuffer> buffer;
+  if (obj->IsJSDataView()) {
+    i::Handle<i::JSDataView> data_view(i::JSDataView::cast(*obj));
+    DCHECK(data_view->buffer()->IsJSArrayBuffer());
+    buffer = i::handle(i::JSArrayBuffer::cast(data_view->buffer()));
+  } else {
+    DCHECK(obj->IsJSTypedArray());
+    buffer = i::JSTypedArray::cast(*obj)->GetBuffer();
+  }
+  return Utils::ToLocal(buffer);
+}
+
+
+size_t v8::ArrayBufferView::ByteOffset() {
+  i::Handle<i::JSArrayBufferView> obj = Utils::OpenHandle(this);
+  return static_cast<size_t>(obj->byte_offset()->Number());
+}
+
+
+size_t v8::ArrayBufferView::ByteLength() {
+  i::Handle<i::JSArrayBufferView> obj = Utils::OpenHandle(this);
+  return static_cast<size_t>(obj->byte_length()->Number());
+}
+
+
+size_t v8::TypedArray::Length() {
+  i::Handle<i::JSTypedArray> obj = Utils::OpenHandle(this);
+  return static_cast<size_t>(obj->length()->Number());
+}
+
+
+static inline void SetupArrayBufferView(
+    i::Isolate* isolate,
+    i::Handle<i::JSArrayBufferView> obj,
+    i::Handle<i::JSArrayBuffer> buffer,
+    size_t byte_offset,
+    size_t byte_length) {
+  DCHECK(byte_offset + byte_length <=
+         static_cast<size_t>(buffer->byte_length()->Number()));
+
+  obj->set_buffer(*buffer);
+
+  obj->set_weak_next(buffer->weak_first_view());
+  buffer->set_weak_first_view(*obj);
+
+  i::Handle<i::Object> byte_offset_object =
+      isolate->factory()->NewNumberFromSize(byte_offset);
+  obj->set_byte_offset(*byte_offset_object);
+
+  i::Handle<i::Object> byte_length_object =
+      isolate->factory()->NewNumberFromSize(byte_length);
+  obj->set_byte_length(*byte_length_object);
+}
+
+template<typename ElementType,
+         ExternalArrayType array_type,
+         i::ElementsKind elements_kind>
+i::Handle<i::JSTypedArray> NewTypedArray(
+    i::Isolate* isolate,
+    Handle<ArrayBuffer> array_buffer, size_t byte_offset, size_t length) {
+  i::Handle<i::JSTypedArray> obj =
+      isolate->factory()->NewJSTypedArray(array_type);
+  i::Handle<i::JSArrayBuffer> buffer = Utils::OpenHandle(*array_buffer);
+
+  DCHECK(byte_offset % sizeof(ElementType) == 0);
+
+  CHECK(length <= (std::numeric_limits<size_t>::max() / sizeof(ElementType)));
+  CHECK(length <= static_cast<size_t>(i::Smi::kMaxValue));
+  size_t byte_length = length * sizeof(ElementType);
+  SetupArrayBufferView(
+      isolate, obj, buffer, byte_offset, byte_length);
+
+  i::Handle<i::Object> length_object =
+      isolate->factory()->NewNumberFromSize(length);
+  obj->set_length(*length_object);
+
+  i::Handle<i::ExternalArray> elements =
+      isolate->factory()->NewExternalArray(
+          static_cast<int>(length), array_type,
+          static_cast<uint8_t*>(buffer->backing_store()) + byte_offset);
+  i::Handle<i::Map> map =
+      i::JSObject::GetElementsTransitionMap(obj, elements_kind);
+  i::JSObject::SetMapAndElements(obj, map, elements);
+  return obj;
+}
+
+
+#define TYPED_ARRAY_NEW(Type, type, TYPE, ctype, size)                       \
+  Local<Type##Array> Type##Array::New(Handle<ArrayBuffer> array_buffer,      \
+                                    size_t byte_offset, size_t length) {     \
+    i::Isolate* isolate = Utils::OpenHandle(*array_buffer)->GetIsolate();    \
+    LOG_API(isolate,                                                         \
+        "v8::" #Type "Array::New(Handle<ArrayBuffer>, size_t, size_t)");     \
+    ENTER_V8(isolate);                                                       \
+    if (!Utils::ApiCheck(length <= static_cast<size_t>(i::Smi::kMaxValue),   \
+            "v8::" #Type "Array::New(Handle<ArrayBuffer>, size_t, size_t)",  \
+            "length exceeds max allowed value")) {                           \
+      return Local<Type##Array>();                                          \
+    }                                                                        \
+    i::Handle<i::JSTypedArray> obj =                                         \
+        NewTypedArray<ctype, v8::kExternal##Type##Array,                     \
+                      i::EXTERNAL_##TYPE##_ELEMENTS>(                        \
+            isolate, array_buffer, byte_offset, length);                     \
+    return Utils::ToLocal##Type##Array(obj);                                 \
+  }
+
+
+TYPED_ARRAYS(TYPED_ARRAY_NEW)
+#undef TYPED_ARRAY_NEW
+
+Local<DataView> DataView::New(Handle<ArrayBuffer> array_buffer,
+                              size_t byte_offset, size_t byte_length) {
+  i::Handle<i::JSArrayBuffer> buffer = Utils::OpenHandle(*array_buffer);
+  i::Isolate* isolate = buffer->GetIsolate();
+  LOG_API(isolate, "v8::DataView::New(void*, size_t, size_t)");
+  ENTER_V8(isolate);
+  i::Handle<i::JSDataView> obj = isolate->factory()->NewJSDataView();
+  SetupArrayBufferView(
+      isolate, obj, buffer, byte_offset, byte_length);
+  return Utils::ToLocal(obj);
+}
+
+
+Local<Symbol> v8::Symbol::New(Isolate* isolate, Local<String> name) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "Symbol::New()");
+  ENTER_V8(i_isolate);
+  i::Handle<i::Symbol> result = i_isolate->factory()->NewSymbol();
+  if (!name.IsEmpty()) result->set_name(*Utils::OpenHandle(*name));
   return Utils::ToLocal(result);
 }
 
 
-Local<Number> v8::Number::New(double value) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Number::New()");
-  if (isnan(value)) {
-    // Introduce only canonical NaN value into the VM, to avoid signaling NaNs.
-    value = i::OS::nan_value();
+static i::Handle<i::Symbol> SymbolFor(i::Isolate* isolate,
+                                      i::Handle<i::String> name,
+                                      i::Handle<i::String> part) {
+  i::Handle<i::JSObject> registry = isolate->GetSymbolRegistry();
+  i::Handle<i::JSObject> symbols =
+      i::Handle<i::JSObject>::cast(
+          i::Object::GetPropertyOrElement(registry, part).ToHandleChecked());
+  i::Handle<i::Object> symbol =
+      i::Object::GetPropertyOrElement(symbols, name).ToHandleChecked();
+  if (!symbol->IsSymbol()) {
+    DCHECK(symbol->IsUndefined());
+    symbol = isolate->factory()->NewSymbol();
+    i::Handle<i::Symbol>::cast(symbol)->set_name(*name);
+    i::JSObject::SetProperty(symbols, name, symbol, i::STRICT).Assert();
   }
-  ENTER_V8(isolate);
-  i::Handle<i::Object> result = isolate->factory()->NewNumber(value);
+  return i::Handle<i::Symbol>::cast(symbol);
+}
+
+
+Local<Symbol> v8::Symbol::For(Isolate* isolate, Local<String> name) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::Handle<i::String> i_name = Utils::OpenHandle(*name);
+  i::Handle<i::String> part = i_isolate->factory()->for_string();
+  return Utils::ToLocal(SymbolFor(i_isolate, i_name, part));
+}
+
+
+Local<Symbol> v8::Symbol::ForApi(Isolate* isolate, Local<String> name) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::Handle<i::String> i_name = Utils::OpenHandle(*name);
+  i::Handle<i::String> part = i_isolate->factory()->for_api_string();
+  return Utils::ToLocal(SymbolFor(i_isolate, i_name, part));
+}
+
+
+static Local<Symbol> GetWellKnownSymbol(Isolate* isolate, const char* name) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::Handle<i::String> i_name =
+      Utils::OpenHandle(*String::NewFromUtf8(isolate, name));
+  i::Handle<i::String> part = i_isolate->factory()->for_intern_string();
+  return Utils::ToLocal(SymbolFor(i_isolate, i_name, part));
+}
+
+
+Local<Symbol> v8::Symbol::GetIterator(Isolate* isolate) {
+  return GetWellKnownSymbol(isolate, "Symbol.iterator");
+}
+
+
+Local<Symbol> v8::Symbol::GetUnscopables(Isolate* isolate) {
+  return GetWellKnownSymbol(isolate, "Symbol.unscopables");
+}
+
+
+Local<Private> v8::Private::New(Isolate* isolate, Local<String> name) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  LOG_API(i_isolate, "Private::New()");
+  ENTER_V8(i_isolate);
+  i::Handle<i::Symbol> symbol = i_isolate->factory()->NewPrivateSymbol();
+  if (!name.IsEmpty()) symbol->set_name(*Utils::OpenHandle(*name));
+  Local<Symbol> result = Utils::ToLocal(symbol);
+  return v8::Handle<Private>(reinterpret_cast<Private*>(*result));
+}
+
+
+Local<Private> v8::Private::ForApi(Isolate* isolate, Local<String> name) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::Handle<i::String> i_name = Utils::OpenHandle(*name);
+  i::Handle<i::JSObject> registry = i_isolate->GetSymbolRegistry();
+  i::Handle<i::String> part = i_isolate->factory()->private_api_string();
+  i::Handle<i::JSObject> privates =
+      i::Handle<i::JSObject>::cast(
+          i::Object::GetPropertyOrElement(registry, part).ToHandleChecked());
+  i::Handle<i::Object> symbol =
+      i::Object::GetPropertyOrElement(privates, i_name).ToHandleChecked();
+  if (!symbol->IsSymbol()) {
+    DCHECK(symbol->IsUndefined());
+    symbol = i_isolate->factory()->NewPrivateSymbol();
+    i::Handle<i::Symbol>::cast(symbol)->set_name(*i_name);
+    i::JSObject::SetProperty(privates, i_name, symbol, i::STRICT).Assert();
+  }
+  Local<Symbol> result = Utils::ToLocal(i::Handle<i::Symbol>::cast(symbol));
+  return v8::Handle<Private>(reinterpret_cast<Private*>(*result));
+}
+
+
+Local<Number> v8::Number::New(Isolate* isolate, double value) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  DCHECK(internal_isolate->IsInitialized());
+  if (std::isnan(value)) {
+    // Introduce only canonical NaN value into the VM, to avoid signaling NaNs.
+    value = base::OS::nan_value();
+  }
+  ENTER_V8(internal_isolate);
+  i::Handle<i::Object> result = internal_isolate->factory()->NewNumber(value);
   return Utils::NumberToLocal(result);
 }
 
 
-Local<Integer> v8::Integer::New(int32_t value) {
-  i::Isolate* isolate = i::Isolate::UncheckedCurrent();
-  EnsureInitializedForIsolate(isolate, "v8::Integer::New()");
+Local<Integer> v8::Integer::New(Isolate* isolate, int32_t value) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  DCHECK(internal_isolate->IsInitialized());
   if (i::Smi::IsValid(value)) {
     return Utils::IntegerToLocal(i::Handle<i::Object>(i::Smi::FromInt(value),
-                                                      isolate));
+                                                      internal_isolate));
   }
-  ENTER_V8(isolate);
-  i::Handle<i::Object> result = isolate->factory()->NewNumber(value);
+  ENTER_V8(internal_isolate);
+  i::Handle<i::Object> result = internal_isolate->factory()->NewNumber(value);
   return Utils::IntegerToLocal(result);
 }
 
 
-Local<Integer> Integer::NewFromUnsigned(uint32_t value) {
+Local<Integer> v8::Integer::NewFromUnsigned(Isolate* isolate, uint32_t value) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  DCHECK(internal_isolate->IsInitialized());
   bool fits_into_int32_t = (value & (1 << 31)) == 0;
   if (fits_into_int32_t) {
-    return Integer::New(static_cast<int32_t>(value));
+    return Integer::New(isolate, static_cast<int32_t>(value));
   }
-  i::Isolate* isolate = i::Isolate::Current();
-  ENTER_V8(isolate);
-  i::Handle<i::Object> result = isolate->factory()->NewNumber(value);
+  ENTER_V8(internal_isolate);
+  i::Handle<i::Object> result = internal_isolate->factory()->NewNumber(value);
   return Utils::IntegerToLocal(result);
 }
 
 
-void V8::IgnoreOutOfMemoryException() {
-  EnterIsolateIfNeeded()->set_ignore_out_of_memory(true);
-}
-
-
 bool V8::AddMessageListener(MessageCallback that, Handle<Value> data) {
   i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::V8::AddMessageListener()");
   ON_BAILOUT(isolate, "v8::V8::AddMessageListener()", return false);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   NeanderArray listeners(isolate->factory()->message_listeners());
-  NeanderObject obj(2);
+  NeanderObject obj(isolate, 2);
   obj.set(0, *isolate->factory()->NewForeign(FUNCTION_ADDR(that)));
-  obj.set(1, data.IsEmpty() ?
-             isolate->heap()->undefined_value() :
-             *Utils::OpenHandle(*data));
+  obj.set(1, data.IsEmpty() ? isolate->heap()->undefined_value()
+          : *Utils::OpenHandle(*data));
   listeners.add(obj.value());
   return true;
 }
@@ -5112,7 +6307,6 @@
 
 void V8::RemoveMessageListeners(MessageCallback that) {
   i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::V8::RemoveMessageListener()");
   ON_BAILOUT(isolate, "v8::V8::RemoveMessageListeners()", return);
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
@@ -5130,9 +6324,9 @@
 
 
 void V8::SetCaptureStackTraceForUncaughtExceptions(
-      bool capture,
-      int frame_limit,
-      StackTrace::StackTraceOptions options) {
+    bool capture,
+    int frame_limit,
+    StackTrace::StackTraceOptions options) {
   i::Isolate::Current()->SetCaptureStackTraceForUncaughtExceptions(
       capture,
       frame_limit,
@@ -5140,113 +6334,162 @@
 }
 
 
-void V8::SetCounterFunction(CounterLookupCallback callback) {
-  i::Isolate* isolate = EnterIsolateIfNeeded();
-  if (IsDeadCheck(isolate, "v8::V8::SetCounterFunction()")) return;
-  isolate->stats_table()->SetCounterFunction(callback);
-}
-
-void V8::SetCreateHistogramFunction(CreateHistogramCallback callback) {
-  i::Isolate* isolate = EnterIsolateIfNeeded();
-  if (IsDeadCheck(isolate, "v8::V8::SetCreateHistogramFunction()")) return;
-  isolate->stats_table()->SetCreateHistogramFunction(callback);
-}
-
-void V8::SetAddHistogramSampleFunction(AddHistogramSampleCallback callback) {
-  i::Isolate* isolate = EnterIsolateIfNeeded();
-  if (IsDeadCheck(isolate, "v8::V8::SetAddHistogramSampleFunction()")) return;
-  isolate->stats_table()->
-      SetAddHistogramSampleFunction(callback);
-}
-
-void V8::EnableSlidingStateWindow() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::EnableSlidingStateWindow()")) return;
-  isolate->logger()->EnableSlidingStateWindow();
-}
-
-
 void V8::SetFailedAccessCheckCallbackFunction(
-      FailedAccessCheckCallback callback) {
+    FailedAccessCheckCallback callback) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::SetFailedAccessCheckCallbackFunction()")) {
-    return;
-  }
   isolate->SetFailedAccessCheckCallback(callback);
 }
 
-void V8::AddObjectGroup(Persistent<Value>* objects,
-                        size_t length,
-                        RetainedObjectInfo* info) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AddObjectGroup()")) return;
-  STATIC_ASSERT(sizeof(Persistent<Value>) == sizeof(i::Object**));
-  isolate->global_handles()->AddObjectGroup(
-      reinterpret_cast<i::Object***>(objects), length, info);
+
+void Isolate::CollectAllGarbage(const char* gc_reason) {
+  reinterpret_cast<i::Isolate*>(this)->heap()->CollectAllGarbage(
+      i::Heap::kNoGCFlags, gc_reason);
 }
 
 
-void V8::AddImplicitReferences(Persistent<Object> parent,
-                               Persistent<Value>* children,
-                               size_t length) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AddImplicitReferences()")) return;
-  STATIC_ASSERT(sizeof(Persistent<Value>) == sizeof(i::Object**));
-  isolate->global_handles()->AddImplicitReferences(
-      i::Handle<i::HeapObject>::cast(Utils::OpenHandle(*parent)).location(),
-      reinterpret_cast<i::Object***>(children), length);
+HeapProfiler* Isolate::GetHeapProfiler() {
+  i::HeapProfiler* heap_profiler =
+      reinterpret_cast<i::Isolate*>(this)->heap_profiler();
+  return reinterpret_cast<HeapProfiler*>(heap_profiler);
 }
 
 
-int V8::AdjustAmountOfExternalAllocatedMemory(int change_in_bytes) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AdjustAmountOfExternalAllocatedMemory()")) {
-    return 0;
+CpuProfiler* Isolate::GetCpuProfiler() {
+  i::CpuProfiler* cpu_profiler =
+      reinterpret_cast<i::Isolate*>(this)->cpu_profiler();
+  return reinterpret_cast<CpuProfiler*>(cpu_profiler);
+}
+
+
+bool Isolate::InContext() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  return isolate->context() != NULL;
+}
+
+
+v8::Local<v8::Context> Isolate::GetCurrentContext() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  i::Context* context = isolate->context();
+  if (context == NULL) return Local<Context>();
+  i::Context* native_context = context->native_context();
+  if (native_context == NULL) return Local<Context>();
+  return Utils::ToLocal(i::Handle<i::Context>(native_context));
+}
+
+
+v8::Local<v8::Context> Isolate::GetCallingContext() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  i::Handle<i::Object> calling = isolate->GetCallingNativeContext();
+  if (calling.is_null()) return Local<Context>();
+  return Utils::ToLocal(i::Handle<i::Context>::cast(calling));
+}
+
+
+v8::Local<v8::Context> Isolate::GetEnteredContext() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  i::Handle<i::Object> last =
+      isolate->handle_scope_implementer()->LastEnteredContext();
+  if (last.is_null()) return Local<Context>();
+  return Utils::ToLocal(i::Handle<i::Context>::cast(last));
+}
+
+
+v8::Local<Value> Isolate::ThrowException(v8::Local<v8::Value> value) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  ENTER_V8(isolate);
+  // If we're passed an empty handle, we throw an undefined exception
+  // to deal more gracefully with out of memory situations.
+  if (value.IsEmpty()) {
+    isolate->ScheduleThrow(isolate->heap()->undefined_value());
+  } else {
+    isolate->ScheduleThrow(*Utils::OpenHandle(*value));
   }
-  return isolate->heap()->AdjustAmountOfExternalAllocatedMemory(
-      change_in_bytes);
+  return v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
 }
 
 
-void V8::SetGlobalGCPrologueCallback(GCCallback callback) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::SetGlobalGCPrologueCallback()")) return;
-  isolate->heap()->SetGlobalGCPrologueCallback(callback);
+void Isolate::SetObjectGroupId(internal::Object** object, UniqueId id) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(this);
+  internal_isolate->global_handles()->SetObjectGroupId(
+      v8::internal::Handle<v8::internal::Object>(object).location(),
+      id);
 }
 
 
-void V8::SetGlobalGCEpilogueCallback(GCCallback callback) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::SetGlobalGCEpilogueCallback()")) return;
-  isolate->heap()->SetGlobalGCEpilogueCallback(callback);
+void Isolate::SetReferenceFromGroup(UniqueId id, internal::Object** object) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(this);
+  internal_isolate->global_handles()->SetReferenceFromGroup(
+      id,
+      v8::internal::Handle<v8::internal::Object>(object).location());
+}
+
+
+void Isolate::SetReference(internal::Object** parent,
+                           internal::Object** child) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(this);
+  i::Object** parent_location =
+      v8::internal::Handle<v8::internal::Object>(parent).location();
+  internal_isolate->global_handles()->SetReference(
+      reinterpret_cast<i::HeapObject**>(parent_location),
+      v8::internal::Handle<v8::internal::Object>(child).location());
+}
+
+
+void Isolate::AddGCPrologueCallback(GCPrologueCallback callback,
+                                    GCType gc_type) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->heap()->AddGCPrologueCallback(callback, gc_type);
+}
+
+
+void Isolate::RemoveGCPrologueCallback(GCPrologueCallback callback) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->heap()->RemoveGCPrologueCallback(callback);
+}
+
+
+void Isolate::AddGCEpilogueCallback(GCEpilogueCallback callback,
+                                    GCType gc_type) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->heap()->AddGCEpilogueCallback(callback, gc_type);
+}
+
+
+void Isolate::RemoveGCEpilogueCallback(GCEpilogueCallback callback) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->heap()->RemoveGCEpilogueCallback(callback);
 }
 
 
 void V8::AddGCPrologueCallback(GCPrologueCallback callback, GCType gc_type) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AddGCPrologueCallback()")) return;
-  isolate->heap()->AddGCPrologueCallback(callback, gc_type);
+  isolate->heap()->AddGCPrologueCallback(
+      reinterpret_cast<v8::Isolate::GCPrologueCallback>(callback),
+      gc_type,
+      false);
 }
 
 
 void V8::RemoveGCPrologueCallback(GCPrologueCallback callback) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::RemoveGCPrologueCallback()")) return;
-  isolate->heap()->RemoveGCPrologueCallback(callback);
+  isolate->heap()->RemoveGCPrologueCallback(
+      reinterpret_cast<v8::Isolate::GCPrologueCallback>(callback));
 }
 
 
 void V8::AddGCEpilogueCallback(GCEpilogueCallback callback, GCType gc_type) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AddGCEpilogueCallback()")) return;
-  isolate->heap()->AddGCEpilogueCallback(callback, gc_type);
+  isolate->heap()->AddGCEpilogueCallback(
+      reinterpret_cast<v8::Isolate::GCEpilogueCallback>(callback),
+      gc_type,
+      false);
 }
 
 
 void V8::RemoveGCEpilogueCallback(GCEpilogueCallback callback) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::RemoveGCEpilogueCallback()")) return;
-  isolate->heap()->RemoveGCEpilogueCallback(callback);
+  isolate->heap()->RemoveGCEpilogueCallback(
+      reinterpret_cast<v8::Isolate::GCEpilogueCallback>(callback));
 }
 
 
@@ -5254,7 +6497,6 @@
                                      ObjectSpace space,
                                      AllocationAction action) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AddMemoryAllocationCallback()")) return;
   isolate->memory_allocator()->AddMemoryAllocationCallback(
       callback, space, action);
 }
@@ -5262,77 +6504,14 @@
 
 void V8::RemoveMemoryAllocationCallback(MemoryAllocationCallback callback) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::RemoveMemoryAllocationCallback()")) return;
   isolate->memory_allocator()->RemoveMemoryAllocationCallback(
       callback);
 }
 
 
-void V8::AddCallCompletedCallback(CallCompletedCallback callback) {
-  if (callback == NULL) return;
-  i::Isolate::EnsureDefaultIsolate();
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::AddLeaveScriptCallback()")) return;
-  i::V8::AddCallCompletedCallback(callback);
-}
-
-
-void V8::RemoveCallCompletedCallback(CallCompletedCallback callback) {
-  i::Isolate::EnsureDefaultIsolate();
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::V8::RemoveLeaveScriptCallback()")) return;
-  i::V8::RemoveCallCompletedCallback(callback);
-}
-
-
-void V8::PauseProfiler() {
-  i::Isolate* isolate = i::Isolate::Current();
-  isolate->logger()->PauseProfiler();
-}
-
-
-void V8::ResumeProfiler() {
-  i::Isolate* isolate = i::Isolate::Current();
-  isolate->logger()->ResumeProfiler();
-}
-
-
-bool V8::IsProfilerPaused() {
-  i::Isolate* isolate = i::Isolate::Current();
-  return isolate->logger()->IsProfilerPaused();
-}
-
-
-int V8::GetCurrentThreadId() {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "V8::GetCurrentThreadId()");
-  return isolate->thread_id().ToInteger();
-}
-
-
-void V8::TerminateExecution(int thread_id) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!isolate->IsInitialized()) return;
-  API_ENTRY_CHECK(isolate, "V8::TerminateExecution()");
-  // If the thread_id identifies the current thread just terminate
-  // execution right away.  Otherwise, ask the thread manager to
-  // terminate the thread with the given id if any.
-  i::ThreadId internal_tid = i::ThreadId::FromInteger(thread_id);
-  if (isolate->thread_id().Equals(internal_tid)) {
-    isolate->stack_guard()->TerminateExecution();
-  } else {
-    isolate->thread_manager()->TerminateExecution(internal_tid);
-  }
-}
-
-
 void V8::TerminateExecution(Isolate* isolate) {
-  // If no isolate is supplied, use the default isolate.
-  if (isolate != NULL) {
-    reinterpret_cast<i::Isolate*>(isolate)->stack_guard()->TerminateExecution();
-  } else {
-    i::Isolate::GetDefaultIsolateStackGuard()->TerminateExecution();
-  }
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i_isolate->stack_guard()->RequestTerminateExecution();
 }
 
 
@@ -5343,23 +6522,81 @@
 }
 
 
+void V8::CancelTerminateExecution(Isolate* isolate) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i_isolate->stack_guard()->ClearTerminateExecution();
+  i_isolate->CancelTerminateExecution();
+}
+
+
+void Isolate::RequestInterrupt(InterruptCallback callback, void* data) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
+  i_isolate->set_api_interrupt_callback(callback);
+  i_isolate->set_api_interrupt_callback_data(data);
+  i_isolate->stack_guard()->RequestApiInterrupt();
+}
+
+
+void Isolate::ClearInterrupt() {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
+  i_isolate->stack_guard()->ClearApiInterrupt();
+  i_isolate->set_api_interrupt_callback(NULL);
+  i_isolate->set_api_interrupt_callback_data(NULL);
+}
+
+
+void Isolate::RequestGarbageCollectionForTesting(GarbageCollectionType type) {
+  CHECK(i::FLAG_expose_gc);
+  if (type == kMinorGarbageCollection) {
+    reinterpret_cast<i::Isolate*>(this)->heap()->CollectGarbage(
+        i::NEW_SPACE, "Isolate::RequestGarbageCollection",
+        kGCCallbackFlagForced);
+  } else {
+    DCHECK_EQ(kFullGarbageCollection, type);
+    reinterpret_cast<i::Isolate*>(this)->heap()->CollectAllGarbage(
+        i::Heap::kAbortIncrementalMarkingMask,
+        "Isolate::RequestGarbageCollection", kGCCallbackFlagForced);
+  }
+}
+
+
 Isolate* Isolate::GetCurrent() {
-  i::Isolate* isolate = i::Isolate::UncheckedCurrent();
+  i::Isolate* isolate = i::Isolate::Current();
   return reinterpret_cast<Isolate*>(isolate);
 }
 
 
-Isolate* Isolate::New() {
+Isolate* Isolate::New(const Isolate::CreateParams& params) {
   i::Isolate* isolate = new i::Isolate();
-  return reinterpret_cast<Isolate*>(isolate);
+  Isolate* v8_isolate = reinterpret_cast<Isolate*>(isolate);
+  if (params.entry_hook) {
+    isolate->set_function_entry_hook(params.entry_hook);
+  }
+  if (params.code_event_handler) {
+    isolate->InitializeLoggingAndCounters();
+    isolate->logger()->SetCodeEventHandler(kJitCodeEventDefault,
+                                           params.code_event_handler);
+  }
+  SetResourceConstraints(isolate, params.constraints);
+  if (params.enable_serializer) {
+    isolate->enable_serializer();
+  }
+  // TODO(jochen): Once we got rid of Isolate::Current(), we can remove this.
+  Isolate::Scope isolate_scope(v8_isolate);
+  if (params.entry_hook || !i::Snapshot::Initialize(isolate)) {
+    // If the isolate has a function entry hook, it needs to re-build all its
+    // code stubs with entry hooks embedded, so don't deserialize a snapshot.
+    isolate->Init(NULL);
+  }
+  return v8_isolate;
 }
 
 
 void Isolate::Dispose() {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
-  if (!ApiCheck(!isolate->IsInUse(),
-                "v8::Isolate::Dispose()",
-                "Disposing the isolate that is entered by a thread.")) {
+  if (!Utils::ApiCheck(!isolate->IsInUse(),
+                       "v8::Isolate::Dispose()",
+                       "Disposing the isolate that is entered by a thread.")) {
     return;
   }
   isolate->TearDown();
@@ -5378,21 +6615,206 @@
 }
 
 
-void Isolate::SetData(void* data) {
-  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
-  isolate->SetData(data);
+Isolate::DisallowJavascriptExecutionScope::DisallowJavascriptExecutionScope(
+    Isolate* isolate,
+    Isolate::DisallowJavascriptExecutionScope::OnFailure on_failure)
+    : on_failure_(on_failure) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  if (on_failure_ == CRASH_ON_FAILURE) {
+    internal_ = reinterpret_cast<void*>(
+        new i::DisallowJavascriptExecution(i_isolate));
+  } else {
+    DCHECK_EQ(THROW_ON_FAILURE, on_failure);
+    internal_ = reinterpret_cast<void*>(
+        new i::ThrowOnJavascriptExecution(i_isolate));
+  }
 }
 
-void* Isolate::GetData() {
+
+Isolate::DisallowJavascriptExecutionScope::~DisallowJavascriptExecutionScope() {
+  if (on_failure_ == CRASH_ON_FAILURE) {
+    delete reinterpret_cast<i::DisallowJavascriptExecution*>(internal_);
+  } else {
+    delete reinterpret_cast<i::ThrowOnJavascriptExecution*>(internal_);
+  }
+}
+
+
+Isolate::AllowJavascriptExecutionScope::AllowJavascriptExecutionScope(
+    Isolate* isolate) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal_assert_ = reinterpret_cast<void*>(
+      new i::AllowJavascriptExecution(i_isolate));
+  internal_throws_ = reinterpret_cast<void*>(
+      new i::NoThrowOnJavascriptExecution(i_isolate));
+}
+
+
+Isolate::AllowJavascriptExecutionScope::~AllowJavascriptExecutionScope() {
+  delete reinterpret_cast<i::AllowJavascriptExecution*>(internal_assert_);
+  delete reinterpret_cast<i::NoThrowOnJavascriptExecution*>(internal_throws_);
+}
+
+
+Isolate::SuppressMicrotaskExecutionScope::SuppressMicrotaskExecutionScope(
+    Isolate* isolate)
+    : isolate_(reinterpret_cast<i::Isolate*>(isolate)) {
+  isolate_->handle_scope_implementer()->IncrementCallDepth();
+}
+
+
+Isolate::SuppressMicrotaskExecutionScope::~SuppressMicrotaskExecutionScope() {
+  isolate_->handle_scope_implementer()->DecrementCallDepth();
+}
+
+
+void Isolate::GetHeapStatistics(HeapStatistics* heap_statistics) {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
-  return isolate->GetData();
+  if (!isolate->IsInitialized()) {
+    heap_statistics->total_heap_size_ = 0;
+    heap_statistics->total_heap_size_executable_ = 0;
+    heap_statistics->total_physical_size_ = 0;
+    heap_statistics->used_heap_size_ = 0;
+    heap_statistics->heap_size_limit_ = 0;
+    return;
+  }
+  i::Heap* heap = isolate->heap();
+  heap_statistics->total_heap_size_ = heap->CommittedMemory();
+  heap_statistics->total_heap_size_executable_ =
+      heap->CommittedMemoryExecutable();
+  heap_statistics->total_physical_size_ = heap->CommittedPhysicalMemory();
+  heap_statistics->used_heap_size_ = heap->SizeOfObjects();
+  heap_statistics->heap_size_limit_ = heap->MaxReserved();
+}
+
+
+void Isolate::SetEventLogger(LogEventCallback that) {
+  // Do not overwrite the event logger if we want to log explicitly.
+  if (i::FLAG_log_timer_events) return;
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->set_event_logger(that);
+}
+
+
+void Isolate::AddCallCompletedCallback(CallCompletedCallback callback) {
+  if (callback == NULL) return;
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->AddCallCompletedCallback(callback);
+}
+
+
+void Isolate::RemoveCallCompletedCallback(CallCompletedCallback callback) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->RemoveCallCompletedCallback(callback);
+}
+
+
+void Isolate::RunMicrotasks() {
+  reinterpret_cast<i::Isolate*>(this)->RunMicrotasks();
+}
+
+
+void Isolate::EnqueueMicrotask(Handle<Function> microtask) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->EnqueueMicrotask(Utils::OpenHandle(*microtask));
+}
+
+
+void Isolate::EnqueueMicrotask(MicrotaskCallback microtask, void* data) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  i::HandleScope scope(isolate);
+  i::Handle<i::CallHandlerInfo> callback_info =
+      i::Handle<i::CallHandlerInfo>::cast(
+          isolate->factory()->NewStruct(i::CALL_HANDLER_INFO_TYPE));
+  SET_FIELD_WRAPPED(callback_info, set_callback, microtask);
+  SET_FIELD_WRAPPED(callback_info, set_data, data);
+  isolate->EnqueueMicrotask(callback_info);
+}
+
+
+void Isolate::SetAutorunMicrotasks(bool autorun) {
+  reinterpret_cast<i::Isolate*>(this)->set_autorun_microtasks(autorun);
+}
+
+
+bool Isolate::WillAutorunMicrotasks() const {
+  return reinterpret_cast<const i::Isolate*>(this)->autorun_microtasks();
+}
+
+
+void Isolate::SetUseCounterCallback(UseCounterCallback callback) {
+  reinterpret_cast<i::Isolate*>(this)->SetUseCounterCallback(callback);
+}
+
+
+void Isolate::SetCounterFunction(CounterLookupCallback callback) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->stats_table()->SetCounterFunction(callback);
+  isolate->InitializeLoggingAndCounters();
+  isolate->counters()->ResetCounters();
+}
+
+
+void Isolate::SetCreateHistogramFunction(CreateHistogramCallback callback) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->stats_table()->SetCreateHistogramFunction(callback);
+  isolate->InitializeLoggingAndCounters();
+  isolate->counters()->ResetHistograms();
+}
+
+
+void Isolate::SetAddHistogramSampleFunction(
+    AddHistogramSampleCallback callback) {
+  reinterpret_cast<i::Isolate*>(this)
+      ->stats_table()
+      ->SetAddHistogramSampleFunction(callback);
+}
+
+
+bool v8::Isolate::IdleNotification(int idle_time_in_ms) {
+  // Returning true tells the caller that it need not
+  // continue to call IdleNotification.
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  if (!i::FLAG_use_idle_notification) return true;
+  return isolate->heap()->IdleNotification(idle_time_in_ms);
+}
+
+
+void v8::Isolate::LowMemoryNotification() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  {
+    i::HistogramTimerScope idle_notification_scope(
+        isolate->counters()->gc_low_memory_notification());
+    isolate->heap()->CollectAllAvailableGarbage("low memory notification");
+  }
+}
+
+
+int v8::Isolate::ContextDisposedNotification() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  return isolate->heap()->NotifyContextDisposed();
+}
+
+
+void v8::Isolate::SetJitCodeEventHandler(JitCodeEventOptions options,
+                                         JitCodeEventHandler event_handler) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  // Ensure that logging is initialized for our isolate.
+  isolate->InitializeLoggingAndCounters();
+  isolate->logger()->SetCodeEventHandler(options, event_handler);
+}
+
+
+void v8::Isolate::SetStackLimit(uintptr_t stack_limit) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  CHECK(stack_limit);
+  isolate->stack_guard()->SetStackLimit(stack_limit);
 }
 
 
 String::Utf8Value::Utf8Value(v8::Handle<v8::Value> obj)
     : str_(NULL), length_(0) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::String::Utf8Value::Utf8Value()")) return;
   if (obj.IsEmpty()) return;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
@@ -5400,7 +6822,7 @@
   Handle<String> str = obj->ToString();
   if (str.IsEmpty()) return;
   i::Handle<i::String> i_str = Utils::OpenHandle(*str);
-  length_ = i::Utf8Length(i_str);
+  length_ = v8::Utf8Length(*i_str, isolate);
   str_ = i::NewArray<char>(length_ + 1);
   str->WriteUtf8(str_);
 }
@@ -5411,31 +6833,9 @@
 }
 
 
-String::AsciiValue::AsciiValue(v8::Handle<v8::Value> obj)
-    : str_(NULL), length_(0) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::String::AsciiValue::AsciiValue()")) return;
-  if (obj.IsEmpty()) return;
-  ENTER_V8(isolate);
-  i::HandleScope scope(isolate);
-  TryCatch try_catch;
-  Handle<String> str = obj->ToString();
-  if (str.IsEmpty()) return;
-  length_ = str->Length();
-  str_ = i::NewArray<char>(length_ + 1);
-  str->WriteAscii(str_);
-}
-
-
-String::AsciiValue::~AsciiValue() {
-  i::DeleteArray(str_);
-}
-
-
 String::Value::Value(v8::Handle<v8::Value> obj)
     : str_(NULL), length_(0) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (IsDeadCheck(isolate, "v8::String::Value::Value()")) return;
   if (obj.IsEmpty()) return;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
@@ -5452,249 +6852,94 @@
   i::DeleteArray(str_);
 }
 
-Local<Value> Exception::RangeError(v8::Handle<v8::String> raw_message) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "RangeError");
-  ON_BAILOUT(isolate, "v8::Exception::RangeError()", return Local<Value>());
-  ENTER_V8(isolate);
-  i::Object* error;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::String> message = Utils::OpenHandle(*raw_message);
-    i::Handle<i::Object> result = isolate->factory()->NewRangeError(message);
-    error = *result;
-  }
-  i::Handle<i::Object> result(error);
-  return Utils::ToLocal(result);
-}
 
-Local<Value> Exception::ReferenceError(v8::Handle<v8::String> raw_message) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "ReferenceError");
-  ON_BAILOUT(isolate, "v8::Exception::ReferenceError()", return Local<Value>());
-  ENTER_V8(isolate);
-  i::Object* error;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::String> message = Utils::OpenHandle(*raw_message);
-    i::Handle<i::Object> result =
-        isolate->factory()->NewReferenceError(message);
-    error = *result;
+#define DEFINE_ERROR(NAME)                                                    \
+  Local<Value> Exception::NAME(v8::Handle<v8::String> raw_message) {          \
+    i::Isolate* isolate = i::Isolate::Current();                              \
+    LOG_API(isolate, #NAME);                                                  \
+    ON_BAILOUT(isolate, "v8::Exception::" #NAME "()", return Local<Value>()); \
+    ENTER_V8(isolate);                                                        \
+    i::Object* error;                                                         \
+    {                                                                         \
+      i::HandleScope scope(isolate);                                          \
+      i::Handle<i::String> message = Utils::OpenHandle(*raw_message);         \
+      i::Handle<i::Object> result;                                            \
+      EXCEPTION_PREAMBLE(isolate);                                            \
+      i::MaybeHandle<i::Object> maybe_result =                                \
+          isolate->factory()->New##NAME(message);                             \
+      has_pending_exception = !maybe_result.ToHandle(&result);                \
+      /* TODO(yangguo): crbug/403509. Return empty handle instead. */         \
+      EXCEPTION_BAILOUT_CHECK(                                                \
+          isolate, v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate)));   \
+      error = *result;                                                        \
+    }                                                                         \
+    i::Handle<i::Object> result(error, isolate);                              \
+    return Utils::ToLocal(result);                                            \
   }
-  i::Handle<i::Object> result(error);
-  return Utils::ToLocal(result);
-}
 
-Local<Value> Exception::SyntaxError(v8::Handle<v8::String> raw_message) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "SyntaxError");
-  ON_BAILOUT(isolate, "v8::Exception::SyntaxError()", return Local<Value>());
-  ENTER_V8(isolate);
-  i::Object* error;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::String> message = Utils::OpenHandle(*raw_message);
-    i::Handle<i::Object> result = isolate->factory()->NewSyntaxError(message);
-    error = *result;
-  }
-  i::Handle<i::Object> result(error);
-  return Utils::ToLocal(result);
-}
+DEFINE_ERROR(RangeError)
+DEFINE_ERROR(ReferenceError)
+DEFINE_ERROR(SyntaxError)
+DEFINE_ERROR(TypeError)
+DEFINE_ERROR(Error)
 
-Local<Value> Exception::TypeError(v8::Handle<v8::String> raw_message) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "TypeError");
-  ON_BAILOUT(isolate, "v8::Exception::TypeError()", return Local<Value>());
-  ENTER_V8(isolate);
-  i::Object* error;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::String> message = Utils::OpenHandle(*raw_message);
-    i::Handle<i::Object> result = isolate->factory()->NewTypeError(message);
-    error = *result;
-  }
-  i::Handle<i::Object> result(error);
-  return Utils::ToLocal(result);
-}
-
-Local<Value> Exception::Error(v8::Handle<v8::String> raw_message) {
-  i::Isolate* isolate = i::Isolate::Current();
-  LOG_API(isolate, "Error");
-  ON_BAILOUT(isolate, "v8::Exception::Error()", return Local<Value>());
-  ENTER_V8(isolate);
-  i::Object* error;
-  {
-    i::HandleScope scope(isolate);
-    i::Handle<i::String> message = Utils::OpenHandle(*raw_message);
-    i::Handle<i::Object> result = isolate->factory()->NewError(message);
-    error = *result;
-  }
-  i::Handle<i::Object> result(error);
-  return Utils::ToLocal(result);
-}
+#undef DEFINE_ERROR
 
 
 // --- D e b u g   S u p p o r t ---
 
-#ifdef ENABLE_DEBUGGER_SUPPORT
-
-static void EventCallbackWrapper(const v8::Debug::EventDetails& event_details) {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (isolate->debug_event_callback() != NULL) {
-    isolate->debug_event_callback()(event_details.GetEvent(),
-                                    event_details.GetExecutionState(),
-                                    event_details.GetEventData(),
-                                    event_details.GetCallbackData());
-  }
-}
-
-
 bool Debug::SetDebugEventListener(EventCallback that, Handle<Value> data) {
   i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Debug::SetDebugEventListener()");
   ON_BAILOUT(isolate, "v8::Debug::SetDebugEventListener()", return false);
   ENTER_V8(isolate);
-
-  isolate->set_debug_event_callback(that);
-
-  i::HandleScope scope(isolate);
-  i::Handle<i::Object> foreign = isolate->factory()->undefined_value();
-  if (that != NULL) {
-    foreign =
-        isolate->factory()->NewForeign(FUNCTION_ADDR(EventCallbackWrapper));
-  }
-  isolate->debugger()->SetEventListener(foreign, Utils::OpenHandle(*data));
-  return true;
-}
-
-
-bool Debug::SetDebugEventListener2(EventCallback2 that, Handle<Value> data) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Debug::SetDebugEventListener2()");
-  ON_BAILOUT(isolate, "v8::Debug::SetDebugEventListener2()", return false);
-  ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::Object> foreign = isolate->factory()->undefined_value();
   if (that != NULL) {
     foreign = isolate->factory()->NewForeign(FUNCTION_ADDR(that));
   }
-  isolate->debugger()->SetEventListener(foreign, Utils::OpenHandle(*data));
-  return true;
-}
-
-
-bool Debug::SetDebugEventListener(v8::Handle<v8::Object> that,
-                                  Handle<Value> data) {
-  i::Isolate* isolate = i::Isolate::Current();
-  ON_BAILOUT(isolate, "v8::Debug::SetDebugEventListener()", return false);
-  ENTER_V8(isolate);
-  isolate->debugger()->SetEventListener(Utils::OpenHandle(*that),
-                                                      Utils::OpenHandle(*data));
+  isolate->debug()->SetEventListener(foreign,
+                                     Utils::OpenHandle(*data, true));
   return true;
 }
 
 
 void Debug::DebugBreak(Isolate* isolate) {
-  // If no isolate is supplied, use the default isolate.
-  if (isolate != NULL) {
-    reinterpret_cast<i::Isolate*>(isolate)->stack_guard()->DebugBreak();
-  } else {
-    i::Isolate::GetDefaultIsolateStackGuard()->DebugBreak();
-  }
+  reinterpret_cast<i::Isolate*>(isolate)->stack_guard()->RequestDebugBreak();
 }
 
 
 void Debug::CancelDebugBreak(Isolate* isolate) {
-  // If no isolate is supplied, use the default isolate.
-  if (isolate != NULL) {
-    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
-    internal_isolate->stack_guard()->Continue(i::DEBUGBREAK);
-  } else {
-    i::Isolate::GetDefaultIsolateStackGuard()->Continue(i::DEBUGBREAK);
-  }
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal_isolate->stack_guard()->ClearDebugBreak();
 }
 
 
-void Debug::DebugBreakForCommand(ClientData* data, Isolate* isolate) {
-  // If no isolate is supplied, use the default isolate.
-  if (isolate != NULL) {
-    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
-    internal_isolate->debugger()->EnqueueDebugCommand(data);
-  } else {
-    i::Isolate::GetDefaultIsolateDebugger()->EnqueueDebugCommand(data);
-  }
+bool Debug::CheckDebugBreak(Isolate* isolate) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  return internal_isolate->stack_guard()->CheckDebugBreak();
 }
 
 
-static void MessageHandlerWrapper(const v8::Debug::Message& message) {
+void Debug::DebugBreakForCommand(Isolate* isolate, ClientData* data) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal_isolate->debug()->EnqueueDebugCommand(data);
+}
+
+
+void Debug::SetMessageHandler(v8::Debug::MessageHandler handler) {
   i::Isolate* isolate = i::Isolate::Current();
-  if (isolate->message_handler()) {
-    v8::String::Value json(message.GetJSON());
-    (isolate->message_handler())(*json, json.length(), message.GetClientData());
-  }
-}
-
-
-void Debug::SetMessageHandler(v8::Debug::MessageHandler handler,
-                              bool message_handler_thread) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Debug::SetMessageHandler");
   ENTER_V8(isolate);
-
-  // Message handler thread not supported any more. Parameter temporally left in
-  // the API for client compatibility reasons.
-  CHECK(!message_handler_thread);
-
-  // TODO(sgjesse) support the old message handler API through a simple wrapper.
-  isolate->set_message_handler(handler);
-  if (handler != NULL) {
-    isolate->debugger()->SetMessageHandler(MessageHandlerWrapper);
-  } else {
-    isolate->debugger()->SetMessageHandler(NULL);
-  }
+  isolate->debug()->SetMessageHandler(handler);
 }
 
 
-void Debug::SetMessageHandler2(v8::Debug::MessageHandler2 handler) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Debug::SetMessageHandler");
-  ENTER_V8(isolate);
-  isolate->debugger()->SetMessageHandler(handler);
-}
-
-
-void Debug::SendCommand(const uint16_t* command, int length,
-                        ClientData* client_data,
-                        Isolate* isolate) {
-  // If no isolate is supplied, use the default isolate.
-  if (isolate != NULL) {
-    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
-    internal_isolate->debugger()->ProcessCommand(
-        i::Vector<const uint16_t>(command, length), client_data);
-  } else {
-    i::Isolate::GetDefaultIsolateDebugger()->ProcessCommand(
-        i::Vector<const uint16_t>(command, length), client_data);
-  }
-}
-
-
-void Debug::SetHostDispatchHandler(HostDispatchHandler handler,
-                                   int period) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Debug::SetHostDispatchHandler");
-  ENTER_V8(isolate);
-  isolate->debugger()->SetHostDispatchHandler(handler, period);
-}
-
-
-void Debug::SetDebugMessageDispatchHandler(
-    DebugMessageDispatchHandler handler, bool provide_locker) {
-  i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate,
-                              "v8::Debug::SetDebugMessageDispatchHandler");
-  ENTER_V8(isolate);
-  isolate->debugger()->SetDebugMessageDispatchHandler(
-      handler, provide_locker);
+void Debug::SendCommand(Isolate* isolate,
+                        const uint16_t* command,
+                        int length,
+                        ClientData* client_data) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal_isolate->debug()->EnqueueCommandMessage(
+      i::Vector<const uint16_t>(command, length), client_data);
 }
 
 
@@ -5704,17 +6949,17 @@
   if (!isolate->IsInitialized()) return Local<Value>();
   ON_BAILOUT(isolate, "v8::Debug::Call()", return Local<Value>());
   ENTER_V8(isolate);
-  i::Handle<i::Object> result;
+  i::MaybeHandle<i::Object> maybe_result;
   EXCEPTION_PREAMBLE(isolate);
   if (data.IsEmpty()) {
-    result = isolate->debugger()->Call(Utils::OpenHandle(*fun),
-                                       isolate->factory()->undefined_value(),
-                                       &has_pending_exception);
+    maybe_result = isolate->debug()->Call(
+        Utils::OpenHandle(*fun), isolate->factory()->undefined_value());
   } else {
-    result = isolate->debugger()->Call(Utils::OpenHandle(*fun),
-                                       Utils::OpenHandle(*data),
-                                       &has_pending_exception);
+    maybe_result = isolate->debug()->Call(
+        Utils::OpenHandle(*fun), Utils::OpenHandle(*data));
   }
+  i::Handle<i::Object> result;
+  has_pending_exception = !maybe_result.ToHandle(&result);
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
   return Utils::ToLocal(result);
 }
@@ -5725,128 +6970,119 @@
   if (!isolate->IsInitialized()) return Local<Value>();
   ON_BAILOUT(isolate, "v8::Debug::GetMirror()", return Local<Value>());
   ENTER_V8(isolate);
-  v8::HandleScope scope;
+  v8::EscapableHandleScope scope(reinterpret_cast<Isolate*>(isolate));
   i::Debug* isolate_debug = isolate->debug();
-  isolate_debug->Load();
-  i::Handle<i::JSObject> debug(isolate_debug->debug_context()->global());
-  i::Handle<i::String> name =
-      isolate->factory()->LookupAsciiSymbol("MakeMirror");
-  i::Handle<i::Object> fun_obj = i::GetProperty(debug, name);
-  i::Handle<i::JSFunction> fun = i::Handle<i::JSFunction>::cast(fun_obj);
-  v8::Handle<v8::Function> v8_fun = Utils::ToLocal(fun);
-  const int kArgc = 1;
-  v8::Handle<v8::Value> argv[kArgc] = { obj };
   EXCEPTION_PREAMBLE(isolate);
-  v8::Handle<v8::Value> result = v8_fun->Call(Utils::ToLocal(debug),
-                                              kArgc,
-                                              argv);
+  has_pending_exception = !isolate_debug->Load();
+  v8::Local<v8::Value> result;
+  if (!has_pending_exception) {
+    i::Handle<i::JSObject> debug(
+        isolate_debug->debug_context()->global_object());
+    i::Handle<i::String> name = isolate->factory()->InternalizeOneByteString(
+        STATIC_CHAR_VECTOR("MakeMirror"));
+    i::Handle<i::Object> fun_obj =
+        i::Object::GetProperty(debug, name).ToHandleChecked();
+    i::Handle<i::JSFunction> fun = i::Handle<i::JSFunction>::cast(fun_obj);
+    v8::Handle<v8::Function> v8_fun = Utils::ToLocal(fun);
+    const int kArgc = 1;
+    v8::Handle<v8::Value> argv[kArgc] = { obj };
+    result = v8_fun->Call(Utils::ToLocal(debug), kArgc, argv);
+    has_pending_exception = result.IsEmpty();
+  }
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
-  return scope.Close(result);
-}
-
-
-bool Debug::EnableAgent(const char* name, int port, bool wait_for_connection) {
-  return i::Isolate::Current()->debugger()->StartAgent(name, port,
-                                                       wait_for_connection);
-}
-
-
-void Debug::DisableAgent() {
-  return i::Isolate::Current()->debugger()->StopAgent();
+  return scope.Escape(result);
 }
 
 
 void Debug::ProcessDebugMessages() {
-  i::Execution::ProcessDebugMessages(true);
+  i::Isolate::Current()->debug()->ProcessDebugMessages(true);
 }
 
+
 Local<Context> Debug::GetDebugContext() {
   i::Isolate* isolate = i::Isolate::Current();
-  EnsureInitializedForIsolate(isolate, "v8::Debug::GetDebugContext()");
   ENTER_V8(isolate);
-  return Utils::ToLocal(i::Isolate::Current()->debugger()->GetDebugContext());
+  return Utils::ToLocal(i::Isolate::Current()->debug()->GetDebugContext());
 }
 
-#endif  // ENABLE_DEBUGGER_SUPPORT
+
+void Debug::SetLiveEditEnabled(Isolate* isolate, bool enable) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal_isolate->debug()->set_live_edit_enabled(enable);
+}
 
 
 Handle<String> CpuProfileNode::GetFunctionName() const {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetFunctionName");
   const i::ProfileNode* node = reinterpret_cast<const i::ProfileNode*>(this);
   const i::CodeEntry* entry = node->entry();
+  i::Handle<i::String> name =
+      isolate->factory()->InternalizeUtf8String(entry->name());
   if (!entry->has_name_prefix()) {
-    return Handle<String>(ToApi<String>(
-        isolate->factory()->LookupAsciiSymbol(entry->name())));
+    return ToApiHandle<String>(name);
   } else {
-    return Handle<String>(ToApi<String>(isolate->factory()->NewConsString(
-        isolate->factory()->LookupAsciiSymbol(entry->name_prefix()),
-        isolate->factory()->LookupAsciiSymbol(entry->name()))));
+    // We do not expect this to fail. Change this if it does.
+    i::Handle<i::String> cons = isolate->factory()->NewConsString(
+        isolate->factory()->InternalizeUtf8String(entry->name_prefix()),
+        name).ToHandleChecked();
+    return ToApiHandle<String>(cons);
   }
 }
 
 
+int CpuProfileNode::GetScriptId() const {
+  const i::ProfileNode* node = reinterpret_cast<const i::ProfileNode*>(this);
+  const i::CodeEntry* entry = node->entry();
+  return entry->script_id();
+}
+
+
 Handle<String> CpuProfileNode::GetScriptResourceName() const {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetScriptResourceName");
   const i::ProfileNode* node = reinterpret_cast<const i::ProfileNode*>(this);
-  return Handle<String>(ToApi<String>(isolate->factory()->LookupAsciiSymbol(
-      node->entry()->resource_name())));
+  return ToApiHandle<String>(isolate->factory()->InternalizeUtf8String(
+      node->entry()->resource_name()));
 }
 
 
 int CpuProfileNode::GetLineNumber() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetLineNumber");
   return reinterpret_cast<const i::ProfileNode*>(this)->entry()->line_number();
 }
 
 
-double CpuProfileNode::GetTotalTime() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetTotalTime");
-  return reinterpret_cast<const i::ProfileNode*>(this)->GetTotalMillis();
+int CpuProfileNode::GetColumnNumber() const {
+  return reinterpret_cast<const i::ProfileNode*>(this)->
+      entry()->column_number();
 }
 
 
-double CpuProfileNode::GetSelfTime() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetSelfTime");
-  return reinterpret_cast<const i::ProfileNode*>(this)->GetSelfMillis();
+const char* CpuProfileNode::GetBailoutReason() const {
+  const i::ProfileNode* node = reinterpret_cast<const i::ProfileNode*>(this);
+  return node->entry()->bailout_reason();
 }
 
 
-double CpuProfileNode::GetTotalSamplesCount() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetTotalSamplesCount");
-  return reinterpret_cast<const i::ProfileNode*>(this)->total_ticks();
-}
-
-
-double CpuProfileNode::GetSelfSamplesCount() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetSelfSamplesCount");
+unsigned CpuProfileNode::GetHitCount() const {
   return reinterpret_cast<const i::ProfileNode*>(this)->self_ticks();
 }
 
 
 unsigned CpuProfileNode::GetCallUid() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetCallUid");
   return reinterpret_cast<const i::ProfileNode*>(this)->entry()->GetCallUid();
 }
 
 
+unsigned CpuProfileNode::GetNodeId() const {
+  return reinterpret_cast<const i::ProfileNode*>(this)->id();
+}
+
+
 int CpuProfileNode::GetChildrenCount() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetChildrenCount");
   return reinterpret_cast<const i::ProfileNode*>(this)->children()->length();
 }
 
 
 const CpuProfileNode* CpuProfileNode::GetChild(int index) const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfileNode::GetChild");
   const i::ProfileNode* child =
       reinterpret_cast<const i::ProfileNode*>(this)->children()->at(index);
   return reinterpret_cast<const CpuProfileNode*>(child);
@@ -5855,99 +7091,96 @@
 
 void CpuProfile::Delete() {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfile::Delete");
-  i::CpuProfiler::DeleteProfile(reinterpret_cast<i::CpuProfile*>(this));
-  if (i::CpuProfiler::GetProfilesCount() == 0 &&
-      !i::CpuProfiler::HasDetachedProfiles()) {
-    // If this was the last profile, clean up all accessory data as well.
-    i::CpuProfiler::DeleteAllProfiles();
-  }
-}
-
-
-unsigned CpuProfile::GetUid() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfile::GetUid");
-  return reinterpret_cast<const i::CpuProfile*>(this)->uid();
+  i::CpuProfiler* profiler = isolate->cpu_profiler();
+  DCHECK(profiler != NULL);
+  profiler->DeleteProfile(reinterpret_cast<i::CpuProfile*>(this));
 }
 
 
 Handle<String> CpuProfile::GetTitle() const {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfile::GetTitle");
   const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
-  return Handle<String>(ToApi<String>(isolate->factory()->LookupAsciiSymbol(
-      profile->title())));
-}
-
-
-const CpuProfileNode* CpuProfile::GetBottomUpRoot() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfile::GetBottomUpRoot");
-  const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
-  return reinterpret_cast<const CpuProfileNode*>(profile->bottom_up()->root());
+  return ToApiHandle<String>(isolate->factory()->InternalizeUtf8String(
+      profile->title()));
 }
 
 
 const CpuProfileNode* CpuProfile::GetTopDownRoot() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfile::GetTopDownRoot");
   const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
   return reinterpret_cast<const CpuProfileNode*>(profile->top_down()->root());
 }
 
 
-int CpuProfiler::GetProfilesCount() {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfiler::GetProfilesCount");
-  return i::CpuProfiler::GetProfilesCount();
+const CpuProfileNode* CpuProfile::GetSample(int index) const {
+  const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
+  return reinterpret_cast<const CpuProfileNode*>(profile->sample(index));
 }
 
 
-const CpuProfile* CpuProfiler::GetProfile(int index,
-                                          Handle<Value> security_token) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfiler::GetProfile");
-  return reinterpret_cast<const CpuProfile*>(
-      i::CpuProfiler::GetProfile(
-          security_token.IsEmpty() ? NULL : *Utils::OpenHandle(*security_token),
-          index));
+int64_t CpuProfile::GetSampleTimestamp(int index) const {
+  const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
+  return (profile->sample_timestamp(index) - base::TimeTicks())
+      .InMicroseconds();
 }
 
 
-const CpuProfile* CpuProfiler::FindProfile(unsigned uid,
-                                           Handle<Value> security_token) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfiler::FindProfile");
-  return reinterpret_cast<const CpuProfile*>(
-      i::CpuProfiler::FindProfile(
-          security_token.IsEmpty() ? NULL : *Utils::OpenHandle(*security_token),
-          uid));
+int64_t CpuProfile::GetStartTime() const {
+  const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
+  return (profile->start_time() - base::TimeTicks()).InMicroseconds();
 }
 
 
-void CpuProfiler::StartProfiling(Handle<String> title) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfiler::StartProfiling");
-  i::CpuProfiler::StartProfiling(*Utils::OpenHandle(*title));
+int64_t CpuProfile::GetEndTime() const {
+  const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
+  return (profile->end_time() - base::TimeTicks()).InMicroseconds();
 }
 
 
-const CpuProfile* CpuProfiler::StopProfiling(Handle<String> title,
-                                             Handle<Value> security_token) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfiler::StopProfiling");
-  return reinterpret_cast<const CpuProfile*>(
-      i::CpuProfiler::StopProfiling(
-          security_token.IsEmpty() ? NULL : *Utils::OpenHandle(*security_token),
+int CpuProfile::GetSamplesCount() const {
+  return reinterpret_cast<const i::CpuProfile*>(this)->samples_count();
+}
+
+
+void CpuProfiler::SetSamplingInterval(int us) {
+  DCHECK(us >= 0);
+  return reinterpret_cast<i::CpuProfiler*>(this)->set_sampling_interval(
+      base::TimeDelta::FromMicroseconds(us));
+}
+
+
+void CpuProfiler::StartProfiling(Handle<String> title, bool record_samples) {
+  reinterpret_cast<i::CpuProfiler*>(this)->StartProfiling(
+      *Utils::OpenHandle(*title), record_samples);
+}
+
+
+void CpuProfiler::StartCpuProfiling(Handle<String> title, bool record_samples) {
+  StartProfiling(title, record_samples);
+}
+
+
+CpuProfile* CpuProfiler::StopProfiling(Handle<String> title) {
+  return reinterpret_cast<CpuProfile*>(
+      reinterpret_cast<i::CpuProfiler*>(this)->StopProfiling(
           *Utils::OpenHandle(*title)));
 }
 
 
-void CpuProfiler::DeleteAllProfiles() {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::CpuProfiler::DeleteAllProfiles");
-  i::CpuProfiler::DeleteAllProfiles();
+const CpuProfile* CpuProfiler::StopCpuProfiling(Handle<String> title) {
+  return StopProfiling(title);
+}
+
+
+void CpuProfiler::SetIdle(bool is_idle) {
+  i::Isolate* isolate = reinterpret_cast<i::CpuProfiler*>(this)->isolate();
+  i::StateTag state = isolate->current_vm_state();
+  DCHECK(state == i::EXTERNAL || state == i::IDLE);
+  if (isolate->js_entry_sp() != NULL) return;
+  if (is_idle) {
+    isolate->set_current_vm_state(i::IDLE);
+  } else if (state == i::IDLE) {
+    isolate->set_current_vm_state(i::EXTERNAL);
+  }
 }
 
 
@@ -5958,44 +7191,38 @@
 
 
 HeapGraphEdge::Type HeapGraphEdge::GetType() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphEdge::GetType");
   return static_cast<HeapGraphEdge::Type>(ToInternal(this)->type());
 }
 
 
 Handle<Value> HeapGraphEdge::GetName() const {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphEdge::GetName");
   i::HeapGraphEdge* edge = ToInternal(this);
   switch (edge->type()) {
     case i::HeapGraphEdge::kContextVariable:
     case i::HeapGraphEdge::kInternal:
     case i::HeapGraphEdge::kProperty:
     case i::HeapGraphEdge::kShortcut:
-      return Handle<String>(ToApi<String>(isolate->factory()->LookupAsciiSymbol(
-          edge->name())));
+    case i::HeapGraphEdge::kWeak:
+      return ToApiHandle<String>(
+          isolate->factory()->InternalizeUtf8String(edge->name()));
     case i::HeapGraphEdge::kElement:
     case i::HeapGraphEdge::kHidden:
-      return Handle<Number>(ToApi<Number>(isolate->factory()->NewNumberFromInt(
-          edge->index())));
+      return ToApiHandle<Number>(
+          isolate->factory()->NewNumberFromInt(edge->index()));
     default: UNREACHABLE();
   }
-  return v8::Undefined();
+  return v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
 }
 
 
 const HeapGraphNode* HeapGraphEdge::GetFromNode() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphEdge::GetFromNode");
-  const i::HeapEntry* from = ToInternal(this)->From();
+  const i::HeapEntry* from = ToInternal(this)->from();
   return reinterpret_cast<const HeapGraphNode*>(from);
 }
 
 
 const HeapGraphNode* HeapGraphEdge::GetToNode() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphEdge::GetToNode");
   const i::HeapEntry* to = ToInternal(this)->to();
   return reinterpret_cast<const HeapGraphNode*>(to);
 }
@@ -6008,85 +7235,42 @@
 
 
 HeapGraphNode::Type HeapGraphNode::GetType() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphNode::GetType");
   return static_cast<HeapGraphNode::Type>(ToInternal(this)->type());
 }
 
 
 Handle<String> HeapGraphNode::GetName() const {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphNode::GetName");
-  return Handle<String>(ToApi<String>(isolate->factory()->LookupAsciiSymbol(
-      ToInternal(this)->name())));
+  return ToApiHandle<String>(
+      isolate->factory()->InternalizeUtf8String(ToInternal(this)->name()));
 }
 
 
-uint64_t HeapGraphNode::GetId() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphNode::GetId");
+SnapshotObjectId HeapGraphNode::GetId() const {
   return ToInternal(this)->id();
 }
 
 
 int HeapGraphNode::GetSelfSize() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphNode::GetSelfSize");
+  size_t size = ToInternal(this)->self_size();
+  CHECK(size <= static_cast<size_t>(internal::kMaxInt));
+  return static_cast<int>(size);
+}
+
+
+size_t HeapGraphNode::GetShallowSize() const {
   return ToInternal(this)->self_size();
 }
 
 
-int HeapGraphNode::GetRetainedSize() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetRetainedSize");
-  return ToInternal(this)->retained_size();
-}
-
-
 int HeapGraphNode::GetChildrenCount() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetChildrenCount");
   return ToInternal(this)->children().length();
 }
 
 
 const HeapGraphEdge* HeapGraphNode::GetChild(int index) const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetChild");
   return reinterpret_cast<const HeapGraphEdge*>(
-      &ToInternal(this)->children()[index]);
-}
-
-
-int HeapGraphNode::GetRetainersCount() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetRetainersCount");
-  return ToInternal(this)->retainers().length();
-}
-
-
-const HeapGraphEdge* HeapGraphNode::GetRetainer(int index) const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetRetainer");
-  return reinterpret_cast<const HeapGraphEdge*>(
-      ToInternal(this)->retainers()[index]);
-}
-
-
-const HeapGraphNode* HeapGraphNode::GetDominatorNode() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetDominatorNode");
-  return reinterpret_cast<const HeapGraphNode*>(ToInternal(this)->dominator());
-}
-
-
-v8::Handle<v8::Value> HeapGraphNode::GetHeapValue() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapGraphNode::GetHeapValue");
-  i::Handle<i::HeapObject> object = ToInternal(this)->GetHeapObject();
-  return v8::Handle<Value>(!object.is_null() ?
-                           ToApi<Value>(object) : ToApi<Value>(
-                               isolate->factory()->undefined_value()));
+      ToInternal(this)->children()[index]);
 }
 
 
@@ -6098,145 +7282,144 @@
 
 void HeapSnapshot::Delete() {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::Delete");
-  if (i::HeapProfiler::GetSnapshotsCount() > 1) {
+  if (isolate->heap_profiler()->GetSnapshotsCount() > 1) {
     ToInternal(this)->Delete();
   } else {
     // If this is the last snapshot, clean up all accessory data as well.
-    i::HeapProfiler::DeleteAllSnapshots();
+    isolate->heap_profiler()->DeleteAllSnapshots();
   }
 }
 
 
-HeapSnapshot::Type HeapSnapshot::GetType() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetType");
-  return static_cast<HeapSnapshot::Type>(ToInternal(this)->type());
-}
-
-
 unsigned HeapSnapshot::GetUid() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetUid");
   return ToInternal(this)->uid();
 }
 
 
 Handle<String> HeapSnapshot::GetTitle() const {
   i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetTitle");
-  return Handle<String>(ToApi<String>(isolate->factory()->LookupAsciiSymbol(
-      ToInternal(this)->title())));
+  return ToApiHandle<String>(
+      isolate->factory()->InternalizeUtf8String(ToInternal(this)->title()));
 }
 
 
 const HeapGraphNode* HeapSnapshot::GetRoot() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetHead");
   return reinterpret_cast<const HeapGraphNode*>(ToInternal(this)->root());
 }
 
 
-const HeapGraphNode* HeapSnapshot::GetNodeById(uint64_t id) const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetNodeById");
+const HeapGraphNode* HeapSnapshot::GetNodeById(SnapshotObjectId id) const {
   return reinterpret_cast<const HeapGraphNode*>(
-      ToInternal(this)->GetEntryById(static_cast<i::SnapshotObjectId>(id)));
+      ToInternal(this)->GetEntryById(id));
 }
 
 
 int HeapSnapshot::GetNodesCount() const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetNodesCount");
-  return ToInternal(this)->entries()->length();
+  return ToInternal(this)->entries().length();
 }
 
 
 const HeapGraphNode* HeapSnapshot::GetNode(int index) const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::GetNode");
   return reinterpret_cast<const HeapGraphNode*>(
-      ToInternal(this)->entries()->at(index));
+      &ToInternal(this)->entries().at(index));
+}
+
+
+SnapshotObjectId HeapSnapshot::GetMaxSnapshotJSObjectId() const {
+  return ToInternal(this)->max_snapshot_js_object_id();
 }
 
 
 void HeapSnapshot::Serialize(OutputStream* stream,
                              HeapSnapshot::SerializationFormat format) const {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapSnapshot::Serialize");
-  ApiCheck(format == kJSON,
-           "v8::HeapSnapshot::Serialize",
-           "Unknown serialization format");
-  ApiCheck(stream->GetOutputEncoding() == OutputStream::kAscii,
-           "v8::HeapSnapshot::Serialize",
-           "Unsupported output encoding");
-  ApiCheck(stream->GetChunkSize() > 0,
-           "v8::HeapSnapshot::Serialize",
-           "Invalid stream chunk size");
+  Utils::ApiCheck(format == kJSON,
+                  "v8::HeapSnapshot::Serialize",
+                  "Unknown serialization format");
+  Utils::ApiCheck(stream->GetChunkSize() > 0,
+                  "v8::HeapSnapshot::Serialize",
+                  "Invalid stream chunk size");
   i::HeapSnapshotJSONSerializer serializer(ToInternal(this));
   serializer.Serialize(stream);
 }
 
 
-int HeapProfiler::GetSnapshotsCount() {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapProfiler::GetSnapshotsCount");
-  return i::HeapProfiler::GetSnapshotsCount();
+int HeapProfiler::GetSnapshotCount() {
+  return reinterpret_cast<i::HeapProfiler*>(this)->GetSnapshotsCount();
 }
 
 
-const HeapSnapshot* HeapProfiler::GetSnapshot(int index) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapProfiler::GetSnapshot");
+const HeapSnapshot* HeapProfiler::GetHeapSnapshot(int index) {
   return reinterpret_cast<const HeapSnapshot*>(
-      i::HeapProfiler::GetSnapshot(index));
+      reinterpret_cast<i::HeapProfiler*>(this)->GetSnapshot(index));
 }
 
 
-const HeapSnapshot* HeapProfiler::FindSnapshot(unsigned uid) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapProfiler::FindSnapshot");
+SnapshotObjectId HeapProfiler::GetObjectId(Handle<Value> value) {
+  i::Handle<i::Object> obj = Utils::OpenHandle(*value);
+  return reinterpret_cast<i::HeapProfiler*>(this)->GetSnapshotObjectId(obj);
+}
+
+
+Handle<Value> HeapProfiler::FindObjectById(SnapshotObjectId id) {
+  i::Handle<i::Object> obj =
+      reinterpret_cast<i::HeapProfiler*>(this)->FindHeapObjectById(id);
+  if (obj.is_null()) return Local<Value>();
+  return Utils::ToLocal(obj);
+}
+
+
+void HeapProfiler::ClearObjectIds() {
+  reinterpret_cast<i::HeapProfiler*>(this)->ClearHeapObjectMap();
+}
+
+
+const HeapSnapshot* HeapProfiler::TakeHeapSnapshot(
+    Handle<String> title,
+    ActivityControl* control,
+    ObjectNameResolver* resolver) {
   return reinterpret_cast<const HeapSnapshot*>(
-      i::HeapProfiler::FindSnapshot(uid));
+      reinterpret_cast<i::HeapProfiler*>(this)->TakeSnapshot(
+          *Utils::OpenHandle(*title), control, resolver));
 }
 
 
-const HeapSnapshot* HeapProfiler::TakeSnapshot(Handle<String> title,
-                                               HeapSnapshot::Type type,
-                                               ActivityControl* control) {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapProfiler::TakeSnapshot");
-  i::HeapSnapshot::Type internal_type = i::HeapSnapshot::kFull;
-  switch (type) {
-    case HeapSnapshot::kFull:
-      internal_type = i::HeapSnapshot::kFull;
-      break;
-    default:
-      UNREACHABLE();
-  }
-  return reinterpret_cast<const HeapSnapshot*>(
-      i::HeapProfiler::TakeSnapshot(
-          *Utils::OpenHandle(*title), internal_type, control));
+void HeapProfiler::StartTrackingHeapObjects(bool track_allocations) {
+  reinterpret_cast<i::HeapProfiler*>(this)->StartHeapObjectsTracking(
+      track_allocations);
 }
 
 
-void HeapProfiler::DeleteAllSnapshots() {
-  i::Isolate* isolate = i::Isolate::Current();
-  IsDeadCheck(isolate, "v8::HeapProfiler::DeleteAllSnapshots");
-  i::HeapProfiler::DeleteAllSnapshots();
+void HeapProfiler::StopTrackingHeapObjects() {
+  reinterpret_cast<i::HeapProfiler*>(this)->StopHeapObjectsTracking();
 }
 
 
-void HeapProfiler::DefineWrapperClass(uint16_t class_id,
-                                      WrapperInfoCallback callback) {
-  i::Isolate::Current()->heap_profiler()->DefineWrapperClass(class_id,
-                                                             callback);
+SnapshotObjectId HeapProfiler::GetHeapStats(OutputStream* stream) {
+  return reinterpret_cast<i::HeapProfiler*>(this)->PushHeapObjectsStats(stream);
 }
 
 
-int HeapProfiler::GetPersistentHandleCount() {
-  i::Isolate* isolate = i::Isolate::Current();
-  return isolate->global_handles()->NumberOfGlobalHandles();
+void HeapProfiler::DeleteAllHeapSnapshots() {
+  reinterpret_cast<i::HeapProfiler*>(this)->DeleteAllSnapshots();
+}
+
+
+void HeapProfiler::SetWrapperClassInfoProvider(uint16_t class_id,
+                                               WrapperInfoCallback callback) {
+  reinterpret_cast<i::HeapProfiler*>(this)->DefineWrapperClass(class_id,
+                                                               callback);
+}
+
+
+size_t HeapProfiler::GetProfilerMemorySize() {
+  return reinterpret_cast<i::HeapProfiler*>(this)->
+      GetMemorySizeUsedByProfiler();
+}
+
+
+void HeapProfiler::SetRetainedObjectInfo(UniqueId id,
+                                         RetainedObjectInfo* info) {
+  reinterpret_cast<i::HeapProfiler*>(this)->SetRetainedObjectInfo(id, info);
 }
 
 
@@ -6248,6 +7431,7 @@
   internal::Testing::set_stress_type(type);
 }
 
+
 int Testing::GetStressRuns() {
   if (internal::FLAG_stress_runs != 0) return internal::FLAG_stress_runs;
 #ifdef DEBUG
@@ -6267,7 +7451,11 @@
 
 void Testing::PrepareStressRun(int run) {
   static const char* kLazyOptimizations =
-      "--prepare-always-opt --nolimit-inlining --noalways-opt";
+      "--prepare-always-opt "
+      "--max-inlined-source-size=999999 "
+      "--max-inlined-nodes=999999 "
+      "--max-inlined-nodes-cumulative=999999 "
+      "--noalways-opt";
   static const char* kForcedOptimizations = "--always-opt";
 
   // If deoptimization stressed turn on frequent deoptimization. If no value
@@ -6296,8 +7484,11 @@
 }
 
 
+// TODO(svenpanne) Deprecate this.
 void Testing::DeoptimizeAll() {
-  internal::Deoptimizer::DeoptimizeAll();
+  i::Isolate* isolate = i::Isolate::Current();
+  i::HandleScope scope(isolate);
+  internal::Deoptimizer::DeoptimizeAll(isolate);
 }
 
 
@@ -6310,10 +7501,9 @@
 
 
 char* HandleScopeImplementer::ArchiveThread(char* storage) {
-  v8::ImplementationUtilities::HandleScopeData* current =
-      isolate_->handle_scope_data();
+  HandleScopeData* current = isolate_->handle_scope_data();
   handle_scope_data_ = *current;
-  memcpy(storage, this, sizeof(*this));
+  MemCopy(storage, this, sizeof(*this));
 
   ResetAfterArchive();
   current->Initialize();
@@ -6328,34 +7518,51 @@
 
 
 char* HandleScopeImplementer::RestoreThread(char* storage) {
-  memcpy(this, storage, sizeof(*this));
+  MemCopy(this, storage, sizeof(*this));
   *isolate_->handle_scope_data() = handle_scope_data_;
   return storage + ArchiveSpacePerThread();
 }
 
 
 void HandleScopeImplementer::IterateThis(ObjectVisitor* v) {
+#ifdef DEBUG
+  bool found_block_before_deferred = false;
+#endif
   // Iterate over all handles in the blocks except for the last.
   for (int i = blocks()->length() - 2; i >= 0; --i) {
     Object** block = blocks()->at(i);
-    v->VisitPointers(block, &block[kHandleBlockSize]);
+    if (last_handle_before_deferred_block_ != NULL &&
+        (last_handle_before_deferred_block_ <= &block[kHandleBlockSize]) &&
+        (last_handle_before_deferred_block_ >= block)) {
+      v->VisitPointers(block, last_handle_before_deferred_block_);
+      DCHECK(!found_block_before_deferred);
+#ifdef DEBUG
+      found_block_before_deferred = true;
+#endif
+    } else {
+      v->VisitPointers(block, &block[kHandleBlockSize]);
+    }
   }
 
+  DCHECK(last_handle_before_deferred_block_ == NULL ||
+         found_block_before_deferred);
+
   // Iterate over live handles in the last block (if any).
   if (!blocks()->is_empty()) {
     v->VisitPointers(blocks()->last(), handle_scope_data_.next);
   }
 
-  if (!saved_contexts_.is_empty()) {
-    Object** start = reinterpret_cast<Object**>(&saved_contexts_.first());
-    v->VisitPointers(start, start + saved_contexts_.length());
+  List<Context*>* context_lists[2] = { &saved_contexts_, &entered_contexts_};
+  for (unsigned i = 0; i < arraysize(context_lists); i++) {
+    if (context_lists[i]->is_empty()) continue;
+    Object** start = reinterpret_cast<Object**>(&context_lists[i]->first());
+    v->VisitPointers(start, start + context_lists[i]->length());
   }
 }
 
 
 void HandleScopeImplementer::Iterate(ObjectVisitor* v) {
-  v8::ImplementationUtilities::HandleScopeData* current =
-      isolate_->handle_scope_data();
+  HandleScopeData* current = isolate_->handle_scope_data();
   handle_scope_data_ = *current;
   IterateThis(v);
 }
@@ -6368,4 +7575,90 @@
   return storage + ArchiveSpacePerThread();
 }
 
+
+DeferredHandles* HandleScopeImplementer::Detach(Object** prev_limit) {
+  DeferredHandles* deferred =
+      new DeferredHandles(isolate()->handle_scope_data()->next, isolate());
+
+  while (!blocks_.is_empty()) {
+    Object** block_start = blocks_.last();
+    Object** block_limit = &block_start[kHandleBlockSize];
+    // We should not need to check for SealHandleScope here. Assert this.
+    DCHECK(prev_limit == block_limit ||
+           !(block_start <= prev_limit && prev_limit <= block_limit));
+    if (prev_limit == block_limit) break;
+    deferred->blocks_.Add(blocks_.last());
+    blocks_.RemoveLast();
+  }
+
+  // deferred->blocks_ now contains the blocks installed on the
+  // HandleScope stack since BeginDeferredScope was called, but in
+  // reverse order.
+
+  DCHECK(prev_limit == NULL || !blocks_.is_empty());
+
+  DCHECK(!blocks_.is_empty() && prev_limit != NULL);
+  DCHECK(last_handle_before_deferred_block_ != NULL);
+  last_handle_before_deferred_block_ = NULL;
+  return deferred;
+}
+
+
+void HandleScopeImplementer::BeginDeferredScope() {
+  DCHECK(last_handle_before_deferred_block_ == NULL);
+  last_handle_before_deferred_block_ = isolate()->handle_scope_data()->next;
+}
+
+
+DeferredHandles::~DeferredHandles() {
+  isolate_->UnlinkDeferredHandles(this);
+
+  for (int i = 0; i < blocks_.length(); i++) {
+#ifdef ENABLE_HANDLE_ZAPPING
+    HandleScope::ZapRange(blocks_[i], &blocks_[i][kHandleBlockSize]);
+#endif
+    isolate_->handle_scope_implementer()->ReturnBlock(blocks_[i]);
+  }
+}
+
+
+void DeferredHandles::Iterate(ObjectVisitor* v) {
+  DCHECK(!blocks_.is_empty());
+
+  DCHECK((first_block_limit_ >= blocks_.first()) &&
+         (first_block_limit_ <= &(blocks_.first())[kHandleBlockSize]));
+
+  v->VisitPointers(blocks_.first(), first_block_limit_);
+
+  for (int i = 1; i < blocks_.length(); i++) {
+    v->VisitPointers(blocks_[i], &blocks_[i][kHandleBlockSize]);
+  }
+}
+
+
+void InvokeAccessorGetterCallback(
+    v8::Local<v8::Name> property,
+    const v8::PropertyCallbackInfo<v8::Value>& info,
+    v8::AccessorNameGetterCallback getter) {
+  // Leaving JavaScript.
+  Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
+  Address getter_address = reinterpret_cast<Address>(reinterpret_cast<intptr_t>(
+      getter));
+  VMState<EXTERNAL> state(isolate);
+  ExternalCallbackScope call_scope(isolate, getter_address);
+  getter(property, info);
+}
+
+
+void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
+                            v8::FunctionCallback callback) {
+  Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
+  Address callback_address =
+      reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
+  VMState<EXTERNAL> state(isolate);
+  ExternalCallbackScope call_scope(isolate, callback_address);
+  callback(info);
+}
+
+
 } }  // namespace v8::internal