diff --git a/ChangeLog b/ChangeLog
index 6d188b8..aeeea78 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2011-08-22: Version 3.5.7
+
+        Make scanner handle invalid unicode escapes in identifiers correctly.
+
+        Make regexp flag parsing stricter.
+
+        Fix several memory leaks.
+
+
 2011-08-17: Version 3.5.6
 
         Fixed issue that could cause crashes when running with --heap-stats.
diff --git a/build/common.gypi b/build/common.gypi
index 5a3da52..c41b2b2 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -32,25 +32,30 @@
     'visibility%': 'hidden',
     'msvs_multi_core_compile%': '1',
     'variables': {
-      'conditions': [
-        [ 'OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
-          # This handles the Linux platforms we generally deal with. Anything
-          # else gets passed through, which probably won't work very well; such
-          # hosts should pass an explicit target_arch to gyp.
-          'host_arch%':
-            '<!(uname -m | sed -e "s/i.86/ia32/;s/x86_64/x64/;s/amd64/x64/;s/arm.*/arm/")',
-        }, {  # OS!="linux" and OS!="freebsd" and OS!="openbsd"
-          'host_arch%': 'ia32',
-        }],
-      ],
+      'variables': {
+        'conditions': [
+          [ 'OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
+            # This handles the Linux platforms we generally deal with. Anything
+            # else gets passed through, which probably won't work very well; such
+            # hosts should pass an explicit target_arch to gyp.
+            'host_arch%':
+              '<!(uname -m | sed -e "s/i.86/ia32/;s/x86_64/x64/;s/amd64/x64/;s/arm.*/arm/")',
+          }, {  # OS!="linux" and OS!="freebsd" and OS!="openbsd"
+            'host_arch%': 'ia32',
+          }],
+        ],
+      },
+      'host_arch%': '<(host_arch)',
+      'target_arch%': '<(host_arch)',
+      'v8_target_arch%': '<(target_arch)',
     },
     'host_arch%': '<(host_arch)',
-    'target_arch%': '<(host_arch)',
-    'v8_target_arch%': '<(target_arch)',
+    'target_arch%': '<(target_arch)',
+    'v8_target_arch%': '<(v8_target_arch)',
     'v8_enable_debugger_support%': 1,
     'conditions': [
-      ['(target_arch=="arm" and host_arch!="arm") or \
-        (target_arch=="x64" and host_arch!="x64")', {
+      ['(v8_target_arch=="arm" and host_arch!="arm") or \
+        (v8_target_arch=="x64" and host_arch!="x64")', {
         'want_separate_host_toolset': 1,
       }, {
         'want_separate_host_toolset': 0,
@@ -80,8 +85,9 @@
   'conditions': [
     [ 'OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"', {
       'target_defaults': {
-        'cflags': [ '-Wall', '-pthread', '-fno-rtti', '-fno-exceptions',
-                    '-pedantic' ],
+        'cflags': [ '-Wall', '-Werror', '-W', '-Wno-unused-parameter',
+                    '-Wnon-virtual-dtor', '-pthread', '-fno-rtti',
+                    '-fno-exceptions', '-pedantic' ],
         'ldflags': [ '-pthread', ],
         'conditions': [
           [ 'target_arch=="ia32"', {
diff --git a/samples/shell.cc b/samples/shell.cc
index f37e731..8ed9d03 100644
--- a/samples/shell.cc
+++ b/samples/shell.cc
@@ -26,39 +26,28 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <v8.h>
-#include <v8-testing.h>
 #include <assert.h>
-#ifdef COMPRESS_STARTUP_DATA_BZ2
-#include <bzlib.h>
-#endif
 #include <fcntl.h>
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
 
-// When building with V8 in a shared library we cannot use functions which
-// is not explicitly a part of the public V8 API. This extensive use of
-// #ifndef USING_V8_SHARED/#endif is a hack until we can resolve whether to
-// still use the shell sample for testing or change to use the developer
-// shell d8 TODO(1272).
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-#include "../src/v8.h"
-#endif  // USING_V8_SHARED
-
-#if !defined(_WIN32) && !defined(_WIN64)
-#include <unistd.h>  // NOLINT
+#ifdef COMPRESS_STARTUP_DATA_BZ2
+#error Using compressed startup data is not supported for this sample
 #endif
 
-static void ExitShell(int exit_code) {
-  // Use _exit instead of exit to avoid races between isolate
-  // threads and static destructors.
-  fflush(stdout);
-  fflush(stderr);
-  _exit(exit_code);
-}
+/**
+ * This sample program shows how to implement a simple javascript shell
+ * based on V8.  This includes initializing V8 with command line options,
+ * creating global functions, compiling and executing strings.
+ *
+ * For a more sophisticated shell, consider using the debug shell D8.
+ */
+
 
 v8::Persistent<v8::Context> CreateShellContext();
 void RunShell(v8::Handle<v8::Context> context);
+int RunMain(int argc, char* argv[]);
 bool ExecuteString(v8::Handle<v8::String> source,
                    v8::Handle<v8::Value> name,
                    bool print_result,
@@ -68,305 +57,28 @@
 v8::Handle<v8::Value> Load(const v8::Arguments& args);
 v8::Handle<v8::Value> Quit(const v8::Arguments& args);
 v8::Handle<v8::Value> Version(const v8::Arguments& args);
-v8::Handle<v8::Value> Int8Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Uint8Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Int16Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Uint16Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Int32Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Uint32Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Float32Array(const v8::Arguments& args);
-v8::Handle<v8::Value> Float64Array(const v8::Arguments& args);
-v8::Handle<v8::Value> PixelArray(const v8::Arguments& args);
 v8::Handle<v8::String> ReadFile(const char* name);
 void ReportException(v8::TryCatch* handler);
 
 
-static bool last_run = true;
-
-class SourceGroup {
- public:
-  SourceGroup() :
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-                  next_semaphore_(v8::internal::OS::CreateSemaphore(0)),
-                  done_semaphore_(v8::internal::OS::CreateSemaphore(0)),
-                  thread_(NULL),
-#endif  // USING_V8_SHARED
-                  argv_(NULL),
-                  begin_offset_(0),
-                  end_offset_(0) { }
-
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-  ~SourceGroup() {
-    delete next_semaphore_;
-    delete done_semaphore_;
-  }
-#endif  // USING_V8_SHARED
-
-  void Begin(char** argv, int offset) {
-    argv_ = const_cast<const char**>(argv);
-    begin_offset_ = offset;
-  }
-
-  void End(int offset) { end_offset_ = offset; }
-
-  void Execute() {
-    for (int i = begin_offset_; i < end_offset_; ++i) {
-      const char* arg = argv_[i];
-      if (strcmp(arg, "-e") == 0 && i + 1 < end_offset_) {
-        // Execute argument given to -e option directly.
-        v8::HandleScope handle_scope;
-        v8::Handle<v8::String> file_name = v8::String::New("unnamed");
-        v8::Handle<v8::String> source = v8::String::New(argv_[i + 1]);
-        if (!ExecuteString(source, file_name, false, true)) {
-          ExitShell(1);
-          return;
-        }
-        ++i;
-      } else if (arg[0] == '-') {
-        // Ignore other options. They have been parsed already.
-      } else {
-        // Use all other arguments as names of files to load and run.
-        v8::HandleScope handle_scope;
-        v8::Handle<v8::String> file_name = v8::String::New(arg);
-        v8::Handle<v8::String> source = ReadFile(arg);
-        if (source.IsEmpty()) {
-          printf("Error reading '%s'\n", arg);
-          continue;
-        }
-        if (!ExecuteString(source, file_name, false, true)) {
-          ExitShell(1);
-          return;
-        }
-      }
-    }
-  }
-
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-  void StartExecuteInThread() {
-    if (thread_ == NULL) {
-      thread_ = new IsolateThread(this);
-      thread_->Start();
-    }
-    next_semaphore_->Signal();
-  }
-
-  void WaitForThread() {
-    if (thread_ == NULL) return;
-    if (last_run) {
-      thread_->Join();
-      thread_ = NULL;
-    } else {
-      done_semaphore_->Wait();
-    }
-  }
-#endif  // USING_V8_SHARED
-
- private:
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-  static v8::internal::Thread::Options GetThreadOptions() {
-    v8::internal::Thread::Options options;
-    options.name = "IsolateThread";
-    // On some systems (OSX 10.6) the stack size default is 0.5Mb or less
-    // which is not enough to parse the big literal expressions used in tests.
-    // The stack size should be at least StackGuard::kLimitSize + some
-    // OS-specific padding for thread startup code.
-    options.stack_size = 2 << 20;  // 2 Mb seems to be enough
-    return options;
-  }
-
-  class IsolateThread : public v8::internal::Thread {
-   public:
-    explicit IsolateThread(SourceGroup* group)
-        : v8::internal::Thread(GetThreadOptions()), group_(group) {}
-
-    virtual void Run() {
-      group_->ExecuteInThread();
-    }
-
-   private:
-    SourceGroup* group_;
-  };
-
-  void ExecuteInThread() {
-    v8::Isolate* isolate = v8::Isolate::New();
-    do {
-      if (next_semaphore_ != NULL) next_semaphore_->Wait();
-      {
-        v8::Isolate::Scope iscope(isolate);
-        v8::HandleScope scope;
-        v8::Persistent<v8::Context> context = CreateShellContext();
-        {
-          v8::Context::Scope cscope(context);
-          Execute();
-        }
-        context.Dispose();
-      }
-      if (done_semaphore_ != NULL) done_semaphore_->Signal();
-    } while (!last_run);
-    isolate->Dispose();
-  }
-
-  v8::internal::Semaphore* next_semaphore_;
-  v8::internal::Semaphore* done_semaphore_;
-  v8::internal::Thread* thread_;
-#endif  // USING_V8_SHARED
-
-  const char** argv_;
-  int begin_offset_;
-  int end_offset_;
-};
+static bool run_shell;
 
 
-static SourceGroup* isolate_sources = NULL;
-
-
-#ifdef COMPRESS_STARTUP_DATA_BZ2
-class BZip2Decompressor : public v8::StartupDataDecompressor {
- public:
-  virtual ~BZip2Decompressor() { }
-
- protected:
-  virtual int DecompressData(char* raw_data,
-                             int* raw_data_size,
-                             const char* compressed_data,
-                             int compressed_data_size) {
-    ASSERT_EQ(v8::StartupData::kBZip2,
-              v8::V8::GetCompressedStartupDataAlgorithm());
-    unsigned int decompressed_size = *raw_data_size;
-    int result =
-        BZ2_bzBuffToBuffDecompress(raw_data,
-                                   &decompressed_size,
-                                   const_cast<char*>(compressed_data),
-                                   compressed_data_size,
-                                   0, 1);
-    if (result == BZ_OK) {
-      *raw_data_size = decompressed_size;
-    }
-    return result;
-  }
-};
-#endif
-
-
-int RunMain(int argc, char* argv[]) {
+int main(int argc, char* argv[]) {
   v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
+  run_shell = (argc == 1);
   v8::HandleScope handle_scope;
   v8::Persistent<v8::Context> context = CreateShellContext();
-  // Enter the newly created execution environment.
-  context->Enter();
   if (context.IsEmpty()) {
     printf("Error creating context\n");
     return 1;
   }
-
-  bool run_shell = (argc == 1);
-  int num_isolates = 1;
-  for (int i = 1; i < argc; i++) {
-    if (strcmp(argv[i], "--isolate") == 0) {
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-      ++num_isolates;
-#else  // USING_V8_SHARED
-      printf("Error: --isolate not supported when linked with shared "
-             "library\n");
-      ExitShell(1);
-#endif  // USING_V8_SHARED
-    }
-  }
-  if (isolate_sources == NULL) {
-    isolate_sources = new SourceGroup[num_isolates];
-    SourceGroup* current = isolate_sources;
-    current->Begin(argv, 1);
-    for (int i = 1; i < argc; i++) {
-      const char* str = argv[i];
-      if (strcmp(str, "--isolate") == 0) {
-        current->End(i);
-        current++;
-        current->Begin(argv, i + 1);
-      } else if (strcmp(str, "--shell") == 0) {
-        run_shell = true;
-      } else if (strcmp(str, "-f") == 0) {
-        // Ignore any -f flags for compatibility with the other stand-
-        // alone JavaScript engines.
-        continue;
-      } else if (strncmp(str, "--", 2) == 0) {
-        printf("Warning: unknown flag %s.\nTry --help for options\n", str);
-      }
-    }
-    current->End(argc);
-  }
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-  for (int i = 1; i < num_isolates; ++i) {
-    isolate_sources[i].StartExecuteInThread();
-  }
-#endif  // USING_V8_SHARED
-  isolate_sources[0].Execute();
+  context->Enter();
+  int result = RunMain(argc, argv);
   if (run_shell) RunShell(context);
-#if !(defined(USING_V8_SHARED) || defined(V8_SHARED))
-  for (int i = 1; i < num_isolates; ++i) {
-    isolate_sources[i].WaitForThread();
-  }
-#endif  // USING_V8_SHARED
-  if (last_run) {
-    delete[] isolate_sources;
-    isolate_sources = NULL;
-  }
   context->Exit();
   context.Dispose();
-  return 0;
-}
-
-
-int main(int argc, char* argv[]) {
-  // Figure out if we're requested to stress the optimization
-  // infrastructure by running tests multiple times and forcing
-  // optimization in the last run.
-  bool FLAG_stress_opt = false;
-  bool FLAG_stress_deopt = false;
-  for (int i = 0; i < argc; i++) {
-    if (strcmp(argv[i], "--stress-opt") == 0) {
-      FLAG_stress_opt = true;
-      argv[i] = NULL;
-    } else if (strcmp(argv[i], "--stress-deopt") == 0) {
-      FLAG_stress_deopt = true;
-      argv[i] = NULL;
-    } else if (strcmp(argv[i], "--noalways-opt") == 0) {
-      // No support for stressing if we can't use --always-opt.
-      FLAG_stress_opt = false;
-      FLAG_stress_deopt = false;
-      break;
-    }
-  }
-
-#ifdef COMPRESS_STARTUP_DATA_BZ2
-  BZip2Decompressor startup_data_decompressor;
-  int bz2_result = startup_data_decompressor.Decompress();
-  if (bz2_result != BZ_OK) {
-    fprintf(stderr, "bzip error code: %d\n", bz2_result);
-    exit(1);
-  }
-#endif
-
-  v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
-  int result = 0;
-  if (FLAG_stress_opt || FLAG_stress_deopt) {
-    v8::Testing::SetStressRunType(FLAG_stress_opt
-                                  ? v8::Testing::kStressTypeOpt
-                                  : v8::Testing::kStressTypeDeopt);
-    int stress_runs = v8::Testing::GetStressRuns();
-    for (int i = 0; i < stress_runs && result == 0; i++) {
-      printf("============ Stress %d/%d ============\n",
-             i + 1, stress_runs);
-      v8::Testing::PrepareStressRun(i);
-      last_run = (i == stress_runs - 1);
-      result = RunMain(argc, argv);
-    }
-    printf("======== Full Deoptimization =======\n");
-    v8::Testing::DeoptimizeAll();
-  } else {
-    result = RunMain(argc, argv);
-  }
   v8::V8::Dispose();
-
   return result;
 }
 
@@ -393,26 +105,6 @@
   // Bind the 'version' function
   global->Set(v8::String::New("version"), v8::FunctionTemplate::New(Version));
 
-  // Bind the handlers for external arrays.
-  global->Set(v8::String::New("Int8Array"),
-              v8::FunctionTemplate::New(Int8Array));
-  global->Set(v8::String::New("Uint8Array"),
-              v8::FunctionTemplate::New(Uint8Array));
-  global->Set(v8::String::New("Int16Array"),
-              v8::FunctionTemplate::New(Int16Array));
-  global->Set(v8::String::New("Uint16Array"),
-              v8::FunctionTemplate::New(Uint16Array));
-  global->Set(v8::String::New("Int32Array"),
-              v8::FunctionTemplate::New(Int32Array));
-  global->Set(v8::String::New("Uint32Array"),
-              v8::FunctionTemplate::New(Uint32Array));
-  global->Set(v8::String::New("Float32Array"),
-              v8::FunctionTemplate::New(Float32Array));
-  global->Set(v8::String::New("Float64Array"),
-              v8::FunctionTemplate::New(Float64Array));
-  global->Set(v8::String::New("PixelArray"),
-              v8::FunctionTemplate::New(PixelArray));
-
   return v8::Context::New(NULL, global);
 }
 
@@ -486,7 +178,9 @@
   // If not arguments are given args[0] will yield undefined which
   // converts to the integer value 0.
   int exit_code = args[0]->Int32Value();
-  ExitShell(exit_code);
+  fflush(stdout);
+  fflush(stderr);
+  exit(exit_code);
   return v8::Undefined();
 }
 
@@ -496,113 +190,6 @@
 }
 
 
-void ExternalArrayWeakCallback(v8::Persistent<v8::Value> object, void* data) {
-  free(data);
-  object.Dispose();
-}
-
-
-v8::Handle<v8::Value> CreateExternalArray(const v8::Arguments& args,
-                                          v8::ExternalArrayType type,
-                                          size_t element_size) {
-  assert(element_size == 1 ||
-         element_size == 2 ||
-         element_size == 4 ||
-         element_size == 8);
-  if (args.Length() != 1) {
-    return v8::ThrowException(
-        v8::String::New("Array constructor needs one parameter."));
-  }
-  static const int kMaxLength = 0x3fffffff;
-  size_t length = 0;
-  if (args[0]->IsUint32()) {
-    length = args[0]->Uint32Value();
-  } else if (args[0]->IsNumber()) {
-    double raw_length = args[0]->NumberValue();
-    if (raw_length < 0) {
-      return v8::ThrowException(
-          v8::String::New("Array length must not be negative."));
-    }
-    if (raw_length > kMaxLength) {
-      return v8::ThrowException(
-          v8::String::New("Array length exceeds maximum length."));
-    }
-    length = static_cast<size_t>(raw_length);
-  } else {
-    return v8::ThrowException(
-        v8::String::New("Array length must be a number."));
-  }
-  if (length > static_cast<size_t>(kMaxLength)) {
-    return v8::ThrowException(
-        v8::String::New("Array length exceeds maximum length."));
-  }
-  void* data = calloc(length, element_size);
-  if (data == NULL) {
-    return v8::ThrowException(v8::String::New("Memory allocation failed."));
-  }
-  v8::Handle<v8::Object> array = v8::Object::New();
-  v8::Persistent<v8::Object> persistent_array =
-      v8::Persistent<v8::Object>::New(array);
-  persistent_array.MakeWeak(data, ExternalArrayWeakCallback);
-  persistent_array.MarkIndependent();
-  array->SetIndexedPropertiesToExternalArrayData(data, type, length);
-  array->Set(v8::String::New("length"), v8::Int32::New(length),
-             v8::ReadOnly);
-  array->Set(v8::String::New("BYTES_PER_ELEMENT"),
-             v8::Int32::New(element_size));
-  return array;
-}
-
-
-v8::Handle<v8::Value> Int8Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalByteArray, sizeof(int8_t));
-}
-
-
-v8::Handle<v8::Value> Uint8Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalUnsignedByteArray,
-                             sizeof(uint8_t));
-}
-
-
-v8::Handle<v8::Value> Int16Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalShortArray, sizeof(int16_t));
-}
-
-
-v8::Handle<v8::Value> Uint16Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalUnsignedShortArray,
-                             sizeof(uint16_t));
-}
-
-v8::Handle<v8::Value> Int32Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalIntArray, sizeof(int32_t));
-}
-
-
-v8::Handle<v8::Value> Uint32Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalUnsignedIntArray,
-                             sizeof(uint32_t));
-}
-
-
-v8::Handle<v8::Value> Float32Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalFloatArray,
-                             sizeof(float));  // NOLINT
-}
-
-
-v8::Handle<v8::Value> Float64Array(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalDoubleArray,
-                             sizeof(double));  // NOLINT
-}
-
-
-v8::Handle<v8::Value> PixelArray(const v8::Arguments& args) {
-  return CreateExternalArray(args, v8::kExternalPixelArray, sizeof(uint8_t));
-}
-
-
 // Reads a file into a v8 string.
 v8::Handle<v8::String> ReadFile(const char* name) {
   FILE* file = fopen(name, "rb");
@@ -625,9 +212,41 @@
 }
 
 
+// Process remaining command line arguments and execute files
+int RunMain(int argc, char* argv[]) {
+  for (int i = 1; i < argc; i++) {
+    const char* str = argv[i];
+    if (strcmp(str, "--shell") == 0) {
+      run_shell = true;
+    } else if (strcmp(str, "-f") == 0) {
+      // Ignore any -f flags for compatibility with the other stand-
+      // alone JavaScript engines.
+      continue;
+    } else if (strncmp(str, "--", 2) == 0) {
+      printf("Warning: unknown flag %s.\nTry --help for options\n", str);
+    } else if (strcmp(str, "-e") == 0 && i + 1 < argc) {
+      // Execute argument given to -e option directly.
+      v8::Handle<v8::String> file_name = v8::String::New("unnamed");
+      v8::Handle<v8::String> source = v8::String::New(argv[++i]);
+      if (!ExecuteString(source, file_name, false, true)) return 1;
+    } else {
+      // Use all other arguments as names of files to load and run.
+      v8::Handle<v8::String> file_name = v8::String::New(str);
+      v8::Handle<v8::String> source = ReadFile(str);
+      if (source.IsEmpty()) {
+        printf("Error reading '%s'\n", str);
+        continue;
+      }
+      if (!ExecuteString(source, file_name, false, true)) return 1;
+    }
+  }
+  return 0;
+}
+
+
 // The read-eval-execute loop of the shell.
 void RunShell(v8::Handle<v8::Context> context) {
-  printf("V8 version %s\n", v8::V8::GetVersion());
+  printf("V8 version %s [sample shell]\n", v8::V8::GetVersion());
   static const int kBufferSize = 256;
   // Enter the execution environment before evaluating any code.
   v8::Context::Scope context_scope(context);
diff --git a/src/api.h b/src/api.h
index ce39d63..07723cb 100644
--- a/src/api.h
+++ b/src/api.h
@@ -406,6 +406,10 @@
         spare_(NULL),
         call_depth_(0) { }
 
+  ~HandleScopeImplementer() {
+    DeleteArray(spare_);
+  }
+
   // Threading support for handle data.
   static int ArchiveSpacePerThread();
   char* RestoreThread(char* from);
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 3116ca4..d8ce956 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -878,7 +878,7 @@
   __ bind(&next_test);
   __ Drop(1);  // Switch value is no longer needed.
   if (default_clause == NULL) {
-    __ b(nested_statement.break_target());
+    __ b(nested_statement.break_label());
   } else {
     __ b(default_clause->body_target());
   }
@@ -892,7 +892,7 @@
     VisitStatements(clause->statements());
   }
 
-  __ bind(nested_statement.break_target());
+  __ bind(nested_statement.break_label());
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
 }
 
@@ -1023,7 +1023,7 @@
   // Load the current count to r0, load the length to r1.
   __ Ldrd(r0, r1, MemOperand(sp, 0 * kPointerSize));
   __ cmp(r0, r1);  // Compare to the array length.
-  __ b(hs, loop_statement.break_target());
+  __ b(hs, loop_statement.break_label());
 
   // Get the current entry of the array into register r3.
   __ ldr(r2, MemOperand(sp, 2 * kPointerSize));
@@ -1049,7 +1049,7 @@
   __ push(r3);  // Current entry.
   __ InvokeBuiltin(Builtins::FILTER_KEY, CALL_FUNCTION);
   __ mov(r3, Operand(r0), SetCC);
-  __ b(eq, loop_statement.continue_target());
+  __ b(eq, loop_statement.continue_label());
 
   // Update the 'each' property or variable from the possibly filtered
   // entry in register r3.
@@ -1065,7 +1065,7 @@
 
   // Generate code for the going to the next element by incrementing
   // the index (smi) stored on top of the stack.
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   __ pop(r0);
   __ add(r0, r0, Operand(Smi::FromInt(1)));
   __ push(r0);
@@ -1074,7 +1074,7 @@
   __ b(&loop);
 
   // Remove the pointers stored on the stack.
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   __ Drop(5);
 
   // Exit and decrement the loop depth.
diff --git a/src/d8.js b/src/d8.js
index 3523e54..a2b9585 100644
--- a/src/d8.js
+++ b/src/d8.js
@@ -392,14 +392,14 @@
           this.frameCommandToJSONRequest_('' +
                                           (Debug.State.currentFrame + 1));
       break;
-      
+
     case 'down':
     case 'do':
       this.request_ =
           this.frameCommandToJSONRequest_('' +
                                           (Debug.State.currentFrame - 1));
       break;
-      
+
     case 'set':
     case 'print':
     case 'p':
@@ -1072,7 +1072,7 @@
         arg2 = 'uncaught';
       }
       excType = arg2;
-      
+
     // Check for:
     //   en[able] [all|unc[aught]] exc[eptions]
     //   dis[able] [all|unc[aught]] exc[eptions]
@@ -1131,7 +1131,7 @@
         request.arguments.ignoreCount = parseInt(otherArgs);
         break;
       default:
-        throw new Error('Invalid arguments.');  
+        throw new Error('Invalid arguments.');
     }
   } else {
     throw new Error('Invalid arguments.');
@@ -1252,7 +1252,7 @@
       start_index = parseInt(args[i]);
       // The user input start index starts at 1:
       if (start_index <= 0) {
-        throw new Error('Invalid index ' + args[i] + '.');                
+        throw new Error('Invalid index ' + args[i] + '.');
       }
       start_index -= 1;
       is_verbose = true;
@@ -2021,7 +2021,7 @@
         } else if (body.breakOnUncaughtExceptions) {
           result += '* breaking on UNCAUGHT exceptions is enabled\n';
         } else {
-          result += '* all exception breakpoints are disabled\n';            
+          result += '* all exception breakpoints are disabled\n';
         }
         details.text = result;
         break;
diff --git a/src/debug-debugger.js b/src/debug-debugger.js
index 36b624e..d254ee5 100644
--- a/src/debug-debugger.js
+++ b/src/debug-debugger.js
@@ -404,7 +404,7 @@
       return this.script_name_ == script.nameOrSourceURL();
     } else if (this.type_ == Debug.ScriptBreakPointType.ScriptRegExp) {
       return this.script_regexp_object_.test(script.nameOrSourceURL());
-    } else { 
+    } else {
       throw new Error("Unexpected breakpoint type " + this.type_);
     }
   }
@@ -1579,7 +1579,7 @@
     response.failed('Missing argument "type" or "target"');
     return;
   }
-  
+
   // Either function or script break point.
   var break_point_number;
   if (type == 'function') {
@@ -1623,10 +1623,10 @@
     break_point_number =
         Debug.setScriptBreakPointByName(target, line, column, condition,
                                         groupId);
-  } else if (type == 'scriptId') { 
+  } else if (type == 'scriptId') {
     break_point_number =
         Debug.setScriptBreakPointById(target, line, column, condition, groupId);
-  } else if (type == 'scriptRegExp') { 
+  } else if (type == 'scriptRegExp') {
     break_point_number =
         Debug.setScriptBreakPointByRegExp(target, line, column, condition,
                                           groupId);
@@ -1797,7 +1797,7 @@
       description.type = 'scriptRegExp';
       description.script_regexp = break_point.script_regexp_object().source;
     } else {
-      throw new Error("Internal error: Unexpected breakpoint type: " + break_point.type()); 
+      throw new Error("Internal error: Unexpected breakpoint type: " + break_point.type());
     }
     array.push(description);
   }
@@ -1838,7 +1838,7 @@
     enabled = !Debug.isBreakOnException();
   } else if (type == 'uncaught') {
     enabled = !Debug.isBreakOnUncaughtException();
-  }  
+  }
 
   // Pull out and check the 'enabled' argument if present:
   if (!IS_UNDEFINED(request.arguments.enabled)) {
@@ -2022,22 +2022,22 @@
   if (!IS_UNDEFINED(frame) && global) {
     return response.failed('Arguments "frame" and "global" are exclusive');
   }
-  
+
   var additional_context_object;
   if (additional_context) {
     additional_context_object = {};
     for (var i = 0; i < additional_context.length; i++) {
       var mapping = additional_context[i];
       if (!IS_STRING(mapping.name) || !IS_NUMBER(mapping.handle)) {
-        return response.failed("Context element #" + i + 
+        return response.failed("Context element #" + i +
             " must contain name:string and handle:number");
-      } 
+      }
       var context_value_mirror = LookupMirror(mapping.handle);
       if (!context_value_mirror) {
         return response.failed("Context object '" + mapping.name +
             "' #" + mapping.handle + "# not found");
       }
-      additional_context_object[mapping.name] = context_value_mirror.value(); 
+      additional_context_object[mapping.name] = context_value_mirror.value();
     }
   }
 
diff --git a/src/elements.cc b/src/elements.cc
index 9927cd5..70d58b3 100644
--- a/src/elements.cc
+++ b/src/elements.cc
@@ -29,6 +29,7 @@
 
 #include "objects.h"
 #include "elements.h"
+#include "utils.h"
 
 namespace v8 {
 namespace internal {
@@ -70,24 +71,34 @@
 // specialization of SomeElementsAccessor methods).
 template <typename ElementsAccessorSubclass, typename BackingStoreClass>
 class ElementsAccessorBase : public ElementsAccessor {
- public:
+ protected:
   ElementsAccessorBase() { }
-  virtual MaybeObject* GetWithReceiver(JSObject* obj,
-                                       Object* receiver,
-                                       uint32_t index) {
-    BackingStoreClass* backing_store = BackingStoreClass::cast(obj->elements());
-    if (index < ElementsAccessorSubclass::GetLength(backing_store)) {
-      return backing_store->get(index);
+  virtual MaybeObject* Get(FixedArrayBase* backing_store,
+                           uint32_t key,
+                           JSObject* obj,
+                           Object* receiver) {
+    return ElementsAccessorSubclass::Get(
+        BackingStoreClass::cast(backing_store), key, obj, receiver);
+  }
+
+  static MaybeObject* Get(BackingStoreClass* backing_store,
+                          uint32_t key,
+                          JSObject* obj,
+                          Object* receiver) {
+    if (key < ElementsAccessorSubclass::GetCapacity(backing_store)) {
+      return backing_store->get(key);
     }
-    return obj->GetHeap()->the_hole_value();
+    return backing_store->GetHeap()->the_hole_value();
   }
 
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) = 0;
 
   virtual MaybeObject* AddElementsToFixedArray(FixedArrayBase* from,
-                                               FixedArray* to) {
+                                               FixedArray* to,
+                                               JSObject* holder,
+                                               Object* receiver) {
     int len0 = to->length();
 #ifdef DEBUG
     if (FLAG_enable_slow_asserts) {
@@ -97,7 +108,7 @@
     }
 #endif
     BackingStoreClass* backing_store = BackingStoreClass::cast(from);
-    int len1 = ElementsAccessorSubclass::GetCapacity(backing_store);
+    uint32_t len1 = ElementsAccessorSubclass::GetCapacity(backing_store);
 
     // Optimize if 'other' is empty.
     // We cannot optimize if 'this' is empty, as other may have holes.
@@ -105,12 +116,22 @@
 
     // Compute how many elements are not in other.
     int extra = 0;
-    for (int y = 0; y < len1; y++) {
-      Object* value;
-      MaybeObject* maybe_value =
-          ElementsAccessorSubclass::GetElementAtCapacityIndex(backing_store, y);
-      if (!maybe_value->ToObject(&value)) return maybe_value;
-      if (!value->IsTheHole() && !HasKey(to, value)) extra++;
+    for (uint32_t y = 0; y < len1; y++) {
+      if (ElementsAccessorSubclass::HasElementAtIndex(backing_store,
+                                                      y,
+                                                      holder,
+                                                      receiver)) {
+        uint32_t key =
+            ElementsAccessorSubclass::GetKeyForIndex(backing_store, y);
+        MaybeObject* maybe_value =
+            ElementsAccessorSubclass::Get(backing_store, key, holder, receiver);
+        Object* value;
+        if (!maybe_value->ToObject(&value)) return maybe_value;
+        ASSERT(!value->IsTheHole());
+        if (!HasKey(to, value)) {
+          extra++;
+        }
+      }
     }
 
     if (extra == 0) return to;
@@ -133,32 +154,67 @@
     }
     // Fill in the extra values.
     int index = 0;
-    for (int y = 0; y < len1; y++) {
-      MaybeObject* maybe_value =
-          ElementsAccessorSubclass::GetElementAtCapacityIndex(backing_store, y);
-      Object* value;
-      if (!maybe_value->ToObject(&value)) return maybe_value;
-      if (!value->IsTheHole() && !HasKey(to, value)) {
-        result->set(len0 + index, value);
-        index++;
+    for (uint32_t y = 0; y < len1; y++) {
+      if (ElementsAccessorSubclass::HasElementAtIndex(backing_store,
+                                                      y,
+                                                      holder,
+                                                      receiver)) {
+        uint32_t key =
+            ElementsAccessorSubclass::GetKeyForIndex(backing_store, y);
+        MaybeObject* maybe_value =
+            ElementsAccessorSubclass::Get(backing_store, key, holder, receiver);
+        Object* value;
+        if (!maybe_value->ToObject(&value)) return maybe_value;
+        if (!value->IsTheHole() && !HasKey(to, value)) {
+          result->set(len0 + index, value);
+          index++;
+        }
       }
     }
     ASSERT(extra == index);
     return result;
   }
 
-  static uint32_t GetLength(BackingStoreClass* backing_store) {
+ protected:
+  static uint32_t GetCapacity(BackingStoreClass* backing_store) {
     return backing_store->length();
   }
 
-  static uint32_t GetCapacity(BackingStoreClass* backing_store) {
-    return GetLength(backing_store);
+  virtual uint32_t GetCapacity(FixedArrayBase* backing_store) {
+    return ElementsAccessorSubclass::GetCapacity(
+        BackingStoreClass::cast(backing_store));
   }
 
-  static MaybeObject* GetElementAtCapacityIndex(
-      BackingStoreClass* backing_store,
-      int index) {
-    return backing_store->get(index);
+  static bool HasElementAtIndex(BackingStoreClass* backing_store,
+                                uint32_t index,
+                                JSObject* holder,
+                                Object* receiver) {
+    uint32_t key =
+        ElementsAccessorSubclass::GetKeyForIndex(backing_store, index);
+    MaybeObject* element = ElementsAccessorSubclass::Get(backing_store,
+                                                         key,
+                                                         holder,
+                                                         receiver);
+    return !element->IsTheHole();
+  }
+
+  virtual bool HasElementAtIndex(FixedArrayBase* backing_store,
+                                 uint32_t index,
+                                 JSObject* holder,
+                                 Object* receiver) {
+    return ElementsAccessorSubclass::HasElementAtIndex(
+        BackingStoreClass::cast(backing_store), index, holder, receiver);
+  }
+
+  static uint32_t GetKeyForIndex(BackingStoreClass* backing_store,
+                                 uint32_t index) {
+    return index;
+  }
+
+  virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store,
+                                              uint32_t index) {
+    return ElementsAccessorSubclass::GetKeyForIndex(
+        BackingStoreClass::cast(backing_store), index);
   }
 
  private:
@@ -170,7 +226,7 @@
     : public ElementsAccessorBase<FastElementsAccessor, FixedArray> {
  public:
   static MaybeObject* DeleteCommon(JSObject* obj,
-                                   uint32_t index) {
+                                   uint32_t key) {
     ASSERT(obj->HasFastElements() || obj->HasFastArgumentsElements());
     Heap* heap = obj->GetHeap();
     FixedArray* backing_store = FixedArray::cast(obj->elements());
@@ -186,8 +242,8 @@
         obj->IsJSArray()
         ? Smi::cast(JSArray::cast(obj)->length())->value()
         : backing_store->length());
-    if (index < length) {
-      backing_store->set_the_hole(index);
+    if (key < length) {
+      backing_store->set_the_hole(key);
       // If an old space backing store is larger than a certain size and
       // has too few used values, normalize it.
       // To avoid doing the check on every delete we require at least
@@ -196,8 +252,8 @@
       const int kMinLengthForSparsenessCheck = 64;
       if (backing_store->length() >= kMinLengthForSparsenessCheck &&
           !heap->InNewSpace(backing_store) &&
-          ((index > 0 && backing_store->get(index - 1) == hole) ||
-           (index + 1 < length && backing_store->get(index + 1) == hole))) {
+          ((key > 0 && backing_store->get(key - 1) == hole) ||
+           (key + 1 < length && backing_store->get(key + 1) == hole))) {
         int num_used = 0;
         for (int i = 0; i < backing_store->length(); ++i) {
           if (backing_store->get(i) != hole) ++num_used;
@@ -213,10 +269,11 @@
     return heap->true_value();
   }
 
+ protected:
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) {
-    return DeleteCommon(obj, index);
+    return DeleteCommon(obj, key);
   }
 };
 
@@ -224,17 +281,28 @@
 class FastDoubleElementsAccessor
     : public ElementsAccessorBase<FastDoubleElementsAccessor,
                                   FixedDoubleArray> {
+ protected:
+  friend class ElementsAccessorBase<FastDoubleElementsAccessor,
+                                    FixedDoubleArray>;
+
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) {
     int length = obj->IsJSArray()
         ? Smi::cast(JSArray::cast(obj)->length())->value()
         : FixedDoubleArray::cast(obj->elements())->length();
-    if (index < static_cast<uint32_t>(length)) {
-      FixedDoubleArray::cast(obj->elements())->set_the_hole(index);
+    if (key < static_cast<uint32_t>(length)) {
+      FixedDoubleArray::cast(obj->elements())->set_the_hole(key);
     }
     return obj->GetHeap()->true_value();
   }
+
+  static bool HasElementAtIndex(FixedDoubleArray* backing_store,
+                                uint32_t index,
+                                JSObject* holder,
+                                Object* receiver) {
+    return !backing_store->is_the_hole(index);
+  }
 };
 
 
@@ -244,20 +312,23 @@
 class ExternalElementsAccessor
     : public ElementsAccessorBase<ExternalElementsAccessorSubclass,
                                   ExternalArray> {
- public:
-  virtual MaybeObject* GetWithReceiver(JSObject* obj,
-                                       Object* receiver,
-                                       uint32_t index) {
-    ExternalArray* backing_store = ExternalArray::cast(obj->elements());
-    if (index < ExternalElementsAccessorSubclass::GetLength(backing_store)) {
-      return backing_store->get(index);
+ protected:
+  friend class ElementsAccessorBase<ExternalElementsAccessorSubclass,
+                                    ExternalArray>;
+
+  static MaybeObject* Get(ExternalArray* backing_store,
+                          uint32_t key,
+                          JSObject* obj,
+                          Object* receiver) {
+    if (key < ExternalElementsAccessorSubclass::GetCapacity(backing_store)) {
+      return backing_store->get(key);
     } else {
-      return obj->GetHeap()->undefined_value();
+      return backing_store->GetHeap()->undefined_value();
     }
   }
 
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) {
     // External arrays always ignore deletes.
     return obj->GetHeap()->true_value();
@@ -323,30 +394,8 @@
     : public ElementsAccessorBase<DictionaryElementsAccessor,
                                   NumberDictionary> {
  public:
-  static MaybeObject* GetNumberDictionaryElement(
-      JSObject* obj,
-      Object* receiver,
-      NumberDictionary* backing_store,
-      uint32_t index) {
-    int entry = backing_store->FindEntry(index);
-    if (entry != NumberDictionary::kNotFound) {
-      Object* element = backing_store->ValueAt(entry);
-      PropertyDetails details = backing_store->DetailsAt(entry);
-      if (details.type() == CALLBACKS) {
-        return obj->GetElementWithCallback(receiver,
-                                           element,
-                                           index,
-                                           obj);
-      } else {
-        return element;
-      }
-    }
-    return obj->GetHeap()->the_hole_value();
-  }
-
-
   static MaybeObject* DeleteCommon(JSObject* obj,
-                                   uint32_t index,
+                                   uint32_t key,
                                    JSReceiver::DeleteMode mode) {
     Isolate* isolate = obj->GetIsolate();
     Heap* heap = isolate->heap();
@@ -357,11 +406,11 @@
       backing_store = FixedArray::cast(backing_store->get(1));
     }
     NumberDictionary* dictionary = NumberDictionary::cast(backing_store);
-    int entry = dictionary->FindEntry(index);
+    int entry = dictionary->FindEntry(key);
     if (entry != NumberDictionary::kNotFound) {
       Object* result = dictionary->DeleteProperty(entry, mode);
       if (result == heap->true_value()) {
-        MaybeObject* maybe_elements = dictionary->Shrink(index);
+        MaybeObject* maybe_elements = dictionary->Shrink(key);
         FixedArray* new_elements = NULL;
         if (!maybe_elements->To(&new_elements)) {
           return maybe_elements;
@@ -378,7 +427,7 @@
         // throws an exception.
         HandleScope scope(isolate);
         Handle<Object> holder(obj);
-        Handle<Object> name = isolate->factory()->NewNumberFromUint(index);
+        Handle<Object> name = isolate->factory()->NewNumberFromUint(key);
         Handle<Object> args[2] = { name, holder };
         Handle<Object> error =
             isolate->factory()->NewTypeError("strict_delete_property",
@@ -389,32 +438,40 @@
     return heap->true_value();
   }
 
+ protected:
+  friend class ElementsAccessorBase<DictionaryElementsAccessor,
+                                    NumberDictionary>;
+
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) {
-    return DeleteCommon(obj, index, mode);
+    return DeleteCommon(obj, key, mode);
   }
 
-  virtual MaybeObject* GetWithReceiver(JSObject* obj,
-                                       Object* receiver,
-                                       uint32_t index) {
-    return GetNumberDictionaryElement(obj,
-                                      receiver,
-                                      obj->element_dictionary(),
-                                      index);
-  }
-
-  static uint32_t GetCapacity(NumberDictionary* dict) {
-    return dict->Capacity();
-  }
-
-  static MaybeObject* GetElementAtCapacityIndex(NumberDictionary* dict,
-                                                int index) {
-    if (dict->IsKey(dict->KeyAt(index))) {
-      return dict->ValueAt(index);
-    } else {
-      return dict->GetHeap()->the_hole_value();
+  static MaybeObject* Get(NumberDictionary* backing_store,
+                          uint32_t key,
+                          JSObject* obj,
+                          Object* receiver) {
+    int entry = backing_store->FindEntry(key);
+    if (entry != NumberDictionary::kNotFound) {
+      Object* element = backing_store->ValueAt(entry);
+      PropertyDetails details = backing_store->DetailsAt(entry);
+      if (details.type() == CALLBACKS) {
+        return obj->GetElementWithCallback(receiver,
+                                           element,
+                                           key,
+                                           obj);
+      } else {
+        return element;
+      }
     }
+    return obj->GetHeap()->the_hole_value();
+  }
+
+  static uint32_t GetKeyForIndex(NumberDictionary* dict,
+                                 uint32_t index) {
+    Object* key = dict->KeyAt(index);
+    return Smi::cast(key)->value();
   }
 };
 
@@ -422,15 +479,16 @@
 class NonStrictArgumentsElementsAccessor
     : public ElementsAccessorBase<NonStrictArgumentsElementsAccessor,
                                   FixedArray> {
- public:
-  virtual MaybeObject* GetWithReceiver(JSObject* obj,
-                                       Object* receiver,
-                                       uint32_t index) {
-    FixedArray* parameter_map = FixedArray::cast(obj->elements());
-    uint32_t length = parameter_map->length();
-    Object* probe =
-        (index < length - 2) ? parameter_map->get(index + 2) : NULL;
-    if (probe != NULL && !probe->IsTheHole()) {
+ protected:
+  friend class ElementsAccessorBase<NonStrictArgumentsElementsAccessor,
+                                    FixedArray>;
+
+  static MaybeObject* Get(FixedArray* parameter_map,
+                          uint32_t key,
+                          JSObject* obj,
+                          Object* receiver) {
+    Object* probe = GetParameterMapArg(parameter_map, key);
+    if (!probe->IsTheHole()) {
       Context* context = Context::cast(parameter_map->get(0));
       int context_index = Smi::cast(probe)->value();
       ASSERT(!context->get(context_index)->IsTheHole());
@@ -438,56 +496,105 @@
     } else {
       // Object is not mapped, defer to the arguments.
       FixedArray* arguments = FixedArray::cast(parameter_map->get(1));
-      if (arguments->IsDictionary()) {
-        return DictionaryElementsAccessor::GetNumberDictionaryElement(
-            obj,
-            receiver,
-            NumberDictionary::cast(arguments),
-            index);
-      } else if (index < static_cast<uint32_t>(arguments->length())) {
-        return arguments->get(index);
-      }
+      return ElementsAccessor::ForArray(arguments)->Get(arguments,
+                                                        key,
+                                                        obj,
+                                                        receiver);
     }
-    return obj->GetHeap()->the_hole_value();
   }
 
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key
+                              ,
                               JSReceiver::DeleteMode mode) {
     FixedArray* parameter_map = FixedArray::cast(obj->elements());
-    uint32_t length = parameter_map->length();
-    Object* probe =
-        index < (length - 2) ? parameter_map->get(index + 2) : NULL;
-    if (probe != NULL && !probe->IsTheHole()) {
+    Object* probe = GetParameterMapArg(parameter_map, key);
+    if (!probe->IsTheHole()) {
       // TODO(kmillikin): We could check if this was the last aliased
       // parameter, and revert to normal elements in that case.  That
       // would enable GC of the context.
-      parameter_map->set_the_hole(index + 2);
+      parameter_map->set_the_hole(key + 2);
     } else {
       FixedArray* arguments = FixedArray::cast(parameter_map->get(1));
       if (arguments->IsDictionary()) {
-        return DictionaryElementsAccessor::DeleteCommon(obj, index, mode);
+        return DictionaryElementsAccessor::DeleteCommon(obj, key, mode);
       } else {
-        return FastElementsAccessor::DeleteCommon(obj, index);
+        return FastElementsAccessor::DeleteCommon(obj, key);
       }
     }
     return obj->GetHeap()->true_value();
   }
 
-  static uint32_t GetCapacity(FixedArray* obj) {
-    // TODO(danno): Return max of parameter map length or backing store
-    // capacity.
-    return 0;
+  static uint32_t GetCapacity(FixedArray* parameter_map) {
+    FixedArrayBase* arguments = FixedArrayBase::cast(parameter_map->get(1));
+    return Max(static_cast<uint32_t>(parameter_map->length() - 2),
+               ForArray(arguments)->GetCapacity(arguments));
   }
 
-  static MaybeObject* GetElementAtCapacityIndex(FixedArray* obj, int index) {
-    // TODO(danno): Return either value from parameter map of backing
-    // store value at index.
-    return obj->GetHeap()->the_hole_value();
+  static uint32_t GetKeyForIndex(FixedArray* dict,
+                                 uint32_t index) {
+    return index;
+  }
+
+  static bool HasElementAtIndex(FixedArray* parameter_map,
+                                uint32_t index,
+                                JSObject* holder,
+                                Object* receiver) {
+    Object* probe = GetParameterMapArg(parameter_map, index);
+    if (!probe->IsTheHole()) {
+      return true;
+    } else {
+      FixedArrayBase* arguments = FixedArrayBase::cast(parameter_map->get(1));
+      ElementsAccessor* accessor = ElementsAccessor::ForArray(arguments);
+      return !accessor->Get(arguments, index, holder, receiver)->IsTheHole();
+    }
+  }
+
+ private:
+  static Object* GetParameterMapArg(FixedArray* parameter_map,
+                                    uint32_t key) {
+    uint32_t length = parameter_map->length();
+    return key < (length - 2 )
+        ? parameter_map->get(key + 2)
+        : parameter_map->GetHeap()->the_hole_value();
   }
 };
 
 
+ElementsAccessor* ElementsAccessor::ForArray(FixedArrayBase* array) {
+  switch (array->map()->instance_type()) {
+    case FIXED_ARRAY_TYPE:
+      if (array->IsDictionary()) {
+        return elements_accessors_[JSObject::DICTIONARY_ELEMENTS];
+      } else {
+        return elements_accessors_[JSObject::FAST_ELEMENTS];
+      }
+    case EXTERNAL_BYTE_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_BYTE_ELEMENTS];
+    case EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_UNSIGNED_BYTE_ELEMENTS];
+    case EXTERNAL_SHORT_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_SHORT_ELEMENTS];
+    case EXTERNAL_UNSIGNED_SHORT_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_UNSIGNED_SHORT_ELEMENTS];
+    case EXTERNAL_INT_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_INT_ELEMENTS];
+    case EXTERNAL_UNSIGNED_INT_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_UNSIGNED_INT_ELEMENTS];
+    case EXTERNAL_FLOAT_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_FLOAT_ELEMENTS];
+    case EXTERNAL_DOUBLE_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_DOUBLE_ELEMENTS];
+    case EXTERNAL_PIXEL_ARRAY_TYPE:
+      return elements_accessors_[JSObject::EXTERNAL_PIXEL_ELEMENTS];
+    default:
+      UNREACHABLE();
+      return NULL;
+      break;
+  }
+}
+
+
 void ElementsAccessor::InitializeOncePerProcess() {
   static struct ConcreteElementsAccessors {
     FastElementsAccessor fast_elements_handler;
diff --git a/src/elements.h b/src/elements.h
index 74e4ad6..3eae303 100644
--- a/src/elements.h
+++ b/src/elements.h
@@ -39,16 +39,19 @@
  public:
   ElementsAccessor() { }
   virtual ~ElementsAccessor() { }
-  virtual MaybeObject* GetWithReceiver(JSObject* obj,
-                                       Object* receiver,
-                                       uint32_t index) = 0;
+  virtual MaybeObject* Get(FixedArrayBase* backing_store,
+                           uint32_t key,
+                           JSObject* holder,
+                           Object* receiver) = 0;
 
-  virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+  virtual MaybeObject* Delete(JSObject* holder,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) = 0;
 
   virtual MaybeObject* AddElementsToFixedArray(FixedArrayBase* from,
-                                               FixedArray* to) = 0;
+                                               FixedArray* to,
+                                               JSObject* holder,
+                                               Object* receiver) = 0;
 
   // Returns a shared ElementsAccessor for the specified ElementsKind.
   static ElementsAccessor* ForKind(JSObject::ElementsKind elements_kind) {
@@ -56,8 +59,31 @@
     return elements_accessors_[elements_kind];
   }
 
+  static ElementsAccessor* ForArray(FixedArrayBase* array);
+
   static void InitializeOncePerProcess();
 
+ protected:
+  friend class NonStrictArgumentsElementsAccessor;
+
+  virtual uint32_t GetCapacity(FixedArrayBase* backing_store) = 0;
+
+  virtual bool HasElementAtIndex(FixedArrayBase* backing_store,
+                                 uint32_t index,
+                                 JSObject* holder,
+                                 Object* receiver) = 0;
+
+  // Element handlers distinguish between indexes and keys when the manipulate
+  // elements.  Indexes refer to elements in terms of their location in the
+  // underlying storage's backing store representation, and are between 0
+  // GetCapacity.  Keys refer to elements in terms of the value that would be
+  // specific in JavaScript to access the element. In most implementations, keys
+  // are equivalent to indexes, and GetKeyForIndex returns the same value it is
+  // passed. In the NumberDictionary ElementsAccessor, GetKeyForIndex maps the
+  // index to a key using the KeyAt method on the NumberDictionary.
+  virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store,
+                                  uint32_t index) = 0;
+
  private:
   static ElementsAccessor** elements_accessors_;
 
diff --git a/src/full-codegen.cc b/src/full-codegen.cc
index 732a8fe..fc7b689 100644
--- a/src/full-codegen.cc
+++ b/src/full-codegen.cc
@@ -862,7 +862,7 @@
   PrepareForBailoutForId(stmt->EntryId(), NO_REGISTERS);
   VisitStatements(stmt->statements());
   scope_ = saved_scope;
-  __ bind(nested_statement.break_target());
+  __ bind(nested_statement.break_label());
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
 }
 
@@ -932,8 +932,7 @@
                       context_register());
   }
 
-  Iteration* loop = current->AsIteration();
-  __ jmp(loop->continue_target());
+  __ jmp(current->AsIteration()->continue_label());
 }
 
 
@@ -961,8 +960,7 @@
                       context_register());
   }
 
-  Breakable* target = current->AsBreakable();
-  __ jmp(target->break_target());
+  __ jmp(current->AsBreakable()->break_label());
 }
 
 
@@ -1030,12 +1028,12 @@
 
   // Record the position of the do while condition and make sure it is
   // possible to break on the condition.
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   PrepareForBailoutForId(stmt->ContinueId(), NO_REGISTERS);
   SetExpressionPosition(stmt->cond(), stmt->condition_position());
   VisitForControl(stmt->cond(),
                   &stack_check,
-                  loop_statement.break_target(),
+                  loop_statement.break_label(),
                   &stack_check);
 
   // Check stack before looping.
@@ -1045,7 +1043,7 @@
   __ jmp(&body);
 
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   decrement_loop_depth();
 }
 
@@ -1066,7 +1064,7 @@
 
   // Emit the statement position here as this is where the while
   // statement code starts.
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   SetStatementPosition(stmt);
 
   // Check stack before looping.
@@ -1075,11 +1073,11 @@
   __ bind(&test);
   VisitForControl(stmt->cond(),
                   &body,
-                  loop_statement.break_target(),
-                  loop_statement.break_target());
+                  loop_statement.break_label(),
+                  loop_statement.break_label());
 
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   decrement_loop_depth();
 }
 
@@ -1102,7 +1100,7 @@
   Visit(stmt->body());
 
   PrepareForBailoutForId(stmt->ContinueId(), NO_REGISTERS);
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   SetStatementPosition(stmt);
   if (stmt->next() != NULL) {
     Visit(stmt->next());
@@ -1119,14 +1117,14 @@
   if (stmt->cond() != NULL) {
     VisitForControl(stmt->cond(),
                     &body,
-                    loop_statement.break_target(),
-                    loop_statement.break_target());
+                    loop_statement.break_label(),
+                    loop_statement.break_label());
   } else {
     __ jmp(&body);
   }
 
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   decrement_loop_depth();
 }
 
@@ -1144,7 +1142,7 @@
   // to introduce a new scope to bind the catch variable and to remove
   // that scope again afterwards.
 
-  Label try_handler_setup, catch_entry, done;
+  Label try_handler_setup, done;
   __ Call(&try_handler_setup);
   // Try handler code, exception in result register.
 
@@ -1170,12 +1168,13 @@
   // Try block code. Sets up the exception handler chain.
   __ bind(&try_handler_setup);
   {
-    TryCatch try_block(this, &catch_entry);
+    const int delta = StackHandlerConstants::kSize / kPointerSize;
+    TryCatch try_block(this);
     __ PushTryHandler(IN_JAVASCRIPT, TRY_CATCH_HANDLER);
-    increment_stack_height(StackHandlerConstants::kSize / kPointerSize);
+    increment_stack_height(delta);
     Visit(stmt->try_block());
     __ PopTryHandler();
-    decrement_stack_height(StackHandlerConstants::kSize / kPointerSize);
+    decrement_stack_height(delta);
   }
   __ bind(&done);
 }
@@ -1208,9 +1207,6 @@
   Label finally_entry;
   Label try_handler_setup;
   const int original_stack_height = stack_height();
-  const int finally_block_stack_height = original_stack_height + 2;
-  const int try_block_stack_height = original_stack_height + 5;
-  STATIC_ASSERT(StackHandlerConstants::kSize == 5 * kPointerSize);
 
   // Setup the try-handler chain. Use a call to
   // Jump to try-handler setup and try-block code. Use call to put try-handler
@@ -1219,9 +1215,9 @@
   // Try handler code. Return address of call is pushed on handler stack.
   {
     // This code is only executed during stack-handler traversal when an
-    // exception is thrown. The execption is in the result register, which
+    // exception is thrown. The exception is in the result register, which
     // is retained by the finally block.
-    // Call the finally block and then rethrow the exception.
+    // Call the finally block and then rethrow the exception if it returns.
     __ Call(&finally_entry);
     __ push(result_register());
     __ CallRuntime(Runtime::kReThrow, 1);
@@ -1232,7 +1228,7 @@
     // Finally block implementation.
     Finally finally_block(this);
     EnterFinallyBlock();
-    set_stack_height(finally_block_stack_height);
+    set_stack_height(original_stack_height + Finally::kElementCount);
     Visit(stmt->finally_block());
     ExitFinallyBlock();  // Return to the calling code.
   }
@@ -1240,9 +1236,10 @@
   __ bind(&try_handler_setup);
   {
     // Setup try handler (stack pointer registers).
+    const int delta = StackHandlerConstants::kSize / kPointerSize;
     TryFinally try_block(this, &finally_entry);
     __ PushTryHandler(IN_JAVASCRIPT, TRY_FINALLY_HANDLER);
-    set_stack_height(try_block_stack_height);
+    set_stack_height(original_stack_height + delta);
     Visit(stmt->try_block());
     __ PopTryHandler();
     set_stack_height(original_stack_height);
diff --git a/src/full-codegen.h b/src/full-codegen.h
index 2fc0553..0ed26a1 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -111,10 +111,7 @@
  private:
   class Breakable;
   class Iteration;
-  class TryCatch;
-  class TryFinally;
-  class Finally;
-  class ForIn;
+
   class TestContext;
 
   class NestedStatement BASE_EMBEDDED {
@@ -132,10 +129,6 @@
 
     virtual Breakable* AsBreakable() { return NULL; }
     virtual Iteration* AsIteration() { return NULL; }
-    virtual TryCatch* AsTryCatch() { return NULL; }
-    virtual TryFinally* AsTryFinally() { return NULL; }
-    virtual Finally* AsFinally() { return NULL; }
-    virtual ForIn* AsForIn() { return NULL; }
 
     virtual bool IsContinueTarget(Statement* target) { return false; }
     virtual bool IsBreakTarget(Statement* target) { return false; }
@@ -158,110 +151,102 @@
     DISALLOW_COPY_AND_ASSIGN(NestedStatement);
   };
 
+  // A breakable statement such as a block.
   class Breakable : public NestedStatement {
    public:
-    Breakable(FullCodeGenerator* codegen,
-              BreakableStatement* break_target)
-        : NestedStatement(codegen),
-          target_(break_target) {}
-    virtual ~Breakable() {}
-    virtual Breakable* AsBreakable() { return this; }
-    virtual bool IsBreakTarget(Statement* statement) {
-      return target_ == statement;
+    Breakable(FullCodeGenerator* codegen, BreakableStatement* statement)
+        : NestedStatement(codegen), statement_(statement) {
     }
-    BreakableStatement* statement() { return target_; }
-    Label* break_target() { return &break_target_label_; }
+    virtual ~Breakable() {}
+
+    virtual Breakable* AsBreakable() { return this; }
+    virtual bool IsBreakTarget(Statement* target) {
+      return statement() == target;
+    }
+
+    BreakableStatement* statement() { return statement_; }
+    Label* break_label() { return &break_label_; }
+
    private:
-    BreakableStatement* target_;
-    Label break_target_label_;
-    DISALLOW_COPY_AND_ASSIGN(Breakable);
+    BreakableStatement* statement_;
+    Label break_label_;
   };
 
+  // An iteration statement such as a while, for, or do loop.
   class Iteration : public Breakable {
    public:
-    Iteration(FullCodeGenerator* codegen,
-              IterationStatement* iteration_statement)
-        : Breakable(codegen, iteration_statement) {}
-    virtual ~Iteration() {}
-    virtual Iteration* AsIteration() { return this; }
-    virtual bool IsContinueTarget(Statement* statement) {
-      return this->statement() == statement;
+    Iteration(FullCodeGenerator* codegen, IterationStatement* statement)
+        : Breakable(codegen, statement) {
     }
-    Label* continue_target() { return &continue_target_label_; }
+    virtual ~Iteration() {}
+
+    virtual Iteration* AsIteration() { return this; }
+    virtual bool IsContinueTarget(Statement* target) {
+      return statement() == target;
+    }
+
+    Label* continue_label() { return &continue_label_; }
+
    private:
-    Label continue_target_label_;
-    DISALLOW_COPY_AND_ASSIGN(Iteration);
+    Label continue_label_;
   };
 
-  // The environment inside the try block of a try/catch statement.
+  // The try block of a try/catch statement.
   class TryCatch : public NestedStatement {
    public:
-    explicit TryCatch(FullCodeGenerator* codegen, Label* catch_entry)
-        : NestedStatement(codegen), catch_entry_(catch_entry) { }
+    explicit TryCatch(FullCodeGenerator* codegen) : NestedStatement(codegen) {
+    }
     virtual ~TryCatch() {}
-    virtual TryCatch* AsTryCatch() { return this; }
-    Label* catch_entry() { return catch_entry_; }
+
     virtual NestedStatement* Exit(int* stack_depth, int* context_length);
-   private:
-    Label* catch_entry_;
-    DISALLOW_COPY_AND_ASSIGN(TryCatch);
   };
 
-  // The environment inside the try block of a try/finally statement.
+  // The try block of a try/finally statement.
   class TryFinally : public NestedStatement {
    public:
-    explicit TryFinally(FullCodeGenerator* codegen, Label* finally_entry)
-        : NestedStatement(codegen), finally_entry_(finally_entry) { }
+    TryFinally(FullCodeGenerator* codegen, Label* finally_entry)
+        : NestedStatement(codegen), finally_entry_(finally_entry) {
+    }
     virtual ~TryFinally() {}
-    virtual TryFinally* AsTryFinally() { return this; }
-    Label* finally_entry() { return finally_entry_; }
+
     virtual NestedStatement* Exit(int* stack_depth, int* context_length);
+
    private:
     Label* finally_entry_;
-    DISALLOW_COPY_AND_ASSIGN(TryFinally);
   };
 
-  // A FinallyEnvironment represents being inside a finally block.
-  // Abnormal termination of the finally block needs to clean up
-  // the block's parameters from the stack.
+  // The finally block of a try/finally statement.
   class Finally : public NestedStatement {
    public:
+    static const int kElementCount = 2;
+
     explicit Finally(FullCodeGenerator* codegen) : NestedStatement(codegen) { }
     virtual ~Finally() {}
-    virtual Finally* AsFinally() { return this; }
+
     virtual NestedStatement* Exit(int* stack_depth, int* context_length) {
-      *stack_depth += kFinallyStackElementCount;
+      *stack_depth += kElementCount;
       return previous_;
     }
-   private:
-    // Number of extra stack slots occupied during a finally block.
-    static const int kFinallyStackElementCount = 2;
-    DISALLOW_COPY_AND_ASSIGN(Finally);
   };
 
-  // A ForInEnvironment represents being inside a for-in loop.
-  // Abnormal termination of the for-in block needs to clean up
-  // the block's temporary storage from the stack.
+  // The body of a for/in loop.
   class ForIn : public Iteration {
    public:
-    ForIn(FullCodeGenerator* codegen,
-          ForInStatement* statement)
-        : Iteration(codegen, statement) { }
+    static const int kElementCount = 5;
+
+    ForIn(FullCodeGenerator* codegen, ForInStatement* statement)
+        : Iteration(codegen, statement) {
+    }
     virtual ~ForIn() {}
-    virtual ForIn* AsForIn() { return this; }
+
     virtual NestedStatement* Exit(int* stack_depth, int* context_length) {
-      *stack_depth += kForInStackElementCount;
+      *stack_depth += kElementCount;
       return previous_;
     }
-   private:
-    static const int kForInStackElementCount = 5;
-    DISALLOW_COPY_AND_ASSIGN(ForIn);
   };
 
 
-  // A WithOrCatch represents being inside the body of a with or catch
-  // statement.  Exiting the body needs to remove a link from the context
-  // chain.
+  // The body of a with or catch.
   class WithOrCatch : public NestedStatement {
    public:
     explicit WithOrCatch(FullCodeGenerator* codegen)
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index bb75b1e..07fd725 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -875,7 +875,7 @@
   __ bind(&next_test);
   __ Drop(1);  // Switch value is no longer needed.
   if (default_clause == NULL) {
-    __ jmp(nested_statement.break_target());
+    __ jmp(nested_statement.break_label());
   } else {
     __ jmp(default_clause->body_target());
   }
@@ -890,7 +890,7 @@
     VisitStatements(clause->statements());
   }
 
-  __ bind(nested_statement.break_target());
+  __ bind(nested_statement.break_label());
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
 }
 
@@ -1006,12 +1006,13 @@
   __ push(eax);  // Fixed array length (as smi).
   __ push(Immediate(Smi::FromInt(0)));  // Initial index.
 
-  increment_stack_height(4);
+  // 1 ~ The object has already been pushed.
+  increment_stack_height(ForIn::kElementCount - 1);
   // Generate code for doing the condition check.
   __ bind(&loop);
   __ mov(eax, Operand(esp, 0 * kPointerSize));  // Get the current index.
   __ cmp(eax, Operand(esp, 1 * kPointerSize));  // Compare to the array length.
-  __ j(above_equal, loop_statement.break_target());
+  __ j(above_equal, loop_statement.break_label());
 
   // Get the current entry of the array into register ebx.
   __ mov(ebx, Operand(esp, 2 * kPointerSize));
@@ -1035,7 +1036,7 @@
   __ push(ebx);  // Current entry.
   __ InvokeBuiltin(Builtins::FILTER_KEY, CALL_FUNCTION);
   __ test(eax, Operand(eax));
-  __ j(equal, loop_statement.continue_target());
+  __ j(equal, loop_statement.continue_label());
   __ mov(ebx, Operand(eax));
 
   // Update the 'each' property or variable from the possibly filtered
@@ -1052,17 +1053,17 @@
 
   // Generate code for going to the next element by incrementing the
   // index (smi) stored on top of the stack.
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   __ add(Operand(esp, 0 * kPointerSize), Immediate(Smi::FromInt(1)));
 
   EmitStackCheck(stmt);
   __ jmp(&loop);
 
   // Remove the pointers stored on the stack.
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   __ add(Operand(esp), Immediate(5 * kPointerSize));
 
-  decrement_stack_height(5);
+  decrement_stack_height(ForIn::kElementCount);
   // Exit and decrement the loop depth.
   __ bind(&exit);
   decrement_loop_depth();
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 04e6cde..9df5cad 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -69,8 +69,8 @@
 
   // Compute number of region covering addr. See Page::GetRegionNumberForAddress
   // method for more details.
-  and_(addr, Page::kPageAlignmentMask);
   shr(addr, Page::kRegionSizeLog2);
+  and_(addr, Page::kPageAlignmentMask >> Page::kRegionSizeLog2);
 
   // Set dirty mark for region.
   // Bit tests with a memory operand should be avoided on Intel processors,
diff --git a/src/isolate.cc b/src/isolate.cc
index eae812b..09cbc8a 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1335,6 +1335,7 @@
   if (list_ == data) list_ = data->next_;
   if (data->next_ != NULL) data->next_->prev_ = data->prev_;
   if (data->prev_ != NULL) data->prev_->next_ = data->next_;
+  delete data;
 }
 
 
@@ -1536,6 +1537,9 @@
   // Has to be called while counters_ are still alive.
   zone_.DeleteKeptSegment();
 
+  delete[] assembler_spare_buffer_;
+  assembler_spare_buffer_ = NULL;
+
   delete unicode_cache_;
   unicode_cache_ = NULL;
 
@@ -1569,6 +1573,8 @@
   handle_scope_implementer_ = NULL;
   delete break_access_;
   break_access_ = NULL;
+  delete debugger_access_;
+  debugger_access_ = NULL;
 
   delete compilation_cache_;
   compilation_cache_ = NULL;
diff --git a/src/json.js b/src/json.js
index 6c984a1..8fd410f 100644
--- a/src/json.js
+++ b/src/json.js
@@ -237,7 +237,7 @@
     }
   }
   stack.pop();
-  builder.push("]"); 
+  builder.push("]");
 }
 
 
diff --git a/src/messages.js b/src/messages.js
index 58c9a53..8ea31ea 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -1,4 +1,4 @@
-// Copyright 2006-2008 the V8 project authors. All rights reserved.
+// Copyright 2011 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:
@@ -57,7 +57,7 @@
   for (var i = 0; i < format.length; i++) {
     var str = format[i];
     for (arg_num = 0; arg_num < kReplacementMarkers.length; arg_num++) {
-      if (format[i] !== kReplacementMarkers[arg_num]) continue;
+      if (str !== kReplacementMarkers[arg_num]) continue;
       try {
         str = ToDetailString(args[arg_num]);
       } catch (e) {
@@ -100,7 +100,8 @@
 
 
 function ToDetailString(obj) {
-  if (obj != null && IS_OBJECT(obj) && obj.toString === $Object.prototype.toString) {
+  if (obj != null && IS_OBJECT(obj) &&
+      obj.toString === $Object.prototype.toString) {
     var constructor = obj.constructor;
     if (!constructor) return ToStringCheckErrorObject(obj);
     var constructorName = constructor.name;
@@ -207,7 +208,7 @@
       stack_overflow:               ["Maximum call stack size exceeded"],
       // SyntaxError
       unable_to_parse:              ["Parse error"],
-      duplicate_regexp_flag:        ["Duplicate RegExp flag ", "%0"],
+      invalid_regexp_flags:         ["Invalid flags supplied to RegExp constructor '", "%0", "'"],
       invalid_regexp:               ["Invalid RegExp pattern /", "%0", "/"],
       illegal_break:                ["Illegal break statement"],
       illegal_continue:             ["Illegal continue statement"],
@@ -560,6 +561,7 @@
   this.end = end;
 }
 
+SourceLocation.prototype.__proto__ = null;
 
 const kLineLengthLimit = 78;
 
@@ -649,6 +651,7 @@
   this.to_position = to_position;
 }
 
+SourceSlice.prototype.__proto__ = null;
 
 /**
  * Get the source text for a SourceSlice
@@ -716,23 +719,28 @@
   this.pos = pos;
 }
 
+CallSite.prototype.__proto__ = null;
+
 CallSite.prototype.getThis = function () {
   return this.receiver;
 };
 
 CallSite.prototype.getTypeName = function () {
   var constructor = this.receiver.constructor;
-  if (!constructor)
+  if (!constructor) {
     return %_CallFunction(this.receiver, ObjectToString);
+  }
   var constructorName = constructor.name;
-  if (!constructorName)
+  if (!constructorName) {
     return %_CallFunction(this.receiver, ObjectToString);
+  }
   return constructorName;
 };
 
 CallSite.prototype.isToplevel = function () {
-  if (this.receiver == null)
+  if (this.receiver == null) {
     return true;
+  }
   return IS_GLOBAL(this.receiver);
 };
 
@@ -765,8 +773,9 @@
   }
   // Maybe this is an evaluation?
   var script = %FunctionGetScript(this.fun);
-  if (script && script.compilation_type == COMPILATION_TYPE_EVAL)
+  if (script && script.compilation_type == COMPILATION_TYPE_EVAL) {
     return "eval";
+  }
   return null;
 };
 
@@ -788,13 +797,15 @@
         this.receiver.__lookupSetter__(prop) === this.fun ||
         (!this.receiver.__lookupGetter__(prop) && this.receiver[prop] === this.fun)) {
       // If we find more than one match bail out to avoid confusion.
-      if (name)
+      if (name) {
         return null;
+      }
       name = prop;
     }
   }
-  if (name)
+  if (name) {
     return name;
+  }
   return null;
 };
 
@@ -804,8 +815,9 @@
 };
 
 CallSite.prototype.getLineNumber = function () {
-  if (this.pos == -1)
+  if (this.pos == -1) {
     return null;
+  }
   var script = %FunctionGetScript(this.fun);
   var location = null;
   if (script) {
@@ -815,8 +827,9 @@
 };
 
 CallSite.prototype.getColumnNumber = function () {
-  if (this.pos == -1)
+  if (this.pos == -1) {
     return null;
+  }
   var script = %FunctionGetScript(this.fun);
   var location = null;
   if (script) {
@@ -836,15 +849,17 @@
 
 CallSite.prototype.isConstructor = function () {
   var constructor = this.receiver ? this.receiver.constructor : null;
-  if (!constructor)
+  if (!constructor) {
     return false;
+  }
   return this.fun === constructor;
 };
 
 function FormatEvalOrigin(script) {
   var sourceURL = script.nameOrSourceURL();
-  if (sourceURL)
+  if (sourceURL) {
     return sourceURL;
+  }
 
   var eval_origin = "eval at ";
   if (script.eval_from_function_name) {
@@ -1042,8 +1057,9 @@
 function captureStackTrace(obj, cons_opt) {
   var stackTraceLimit = $Error.stackTraceLimit;
   if (!stackTraceLimit || !IS_NUMBER(stackTraceLimit)) return;
-  if (stackTraceLimit < 0 || stackTraceLimit > 10000)
+  if (stackTraceLimit < 0 || stackTraceLimit > 10000) {
     stackTraceLimit = 10000;
+  }
   var raw_stack = %CollectStackTrace(cons_opt
                                      ? cons_opt
                                      : captureStackTrace, stackTraceLimit);
@@ -1117,8 +1133,10 @@
   } catch(e) {
     // If this error message was encountered already return the empty
     // string for it instead of recursively formatting it.
-    if (isCyclicErrorMarker(e)) return '';
-    else throw e;
+    if (isCyclicErrorMarker(e)) {
+      return '';
+    }
+    throw e;
   }
 }
 
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index d8909c9..e1a23b4 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -747,9 +747,9 @@
         __ li(a2, Operand(variable->name()));
         // Declaration nodes are always introduced in one of two modes.
         ASSERT(mode == Variable::VAR ||
-               mode == Variable::CONST);
-        PropertyAttributes attr =
-            (mode == Variable::VAR) ? NONE : READ_ONLY;
+               mode == Variable::CONST ||
+               mode == Variable::LET);
+        PropertyAttributes attr = (mode == Variable::CONST) ? READ_ONLY : NONE;
         __ li(a1, Operand(Smi::FromInt(attr)));
         // Push initial value, if any.
         // Note: For variables we must not push an initial value (such as
@@ -886,7 +886,7 @@
   __ bind(&next_test);
   __ Drop(1);  // Switch value is no longer needed.
   if (default_clause == NULL) {
-    __ Branch(nested_statement.break_target());
+    __ Branch(nested_statement.break_label());
   } else {
     __ Branch(default_clause->body_target());
   }
@@ -900,7 +900,7 @@
     VisitStatements(clause->statements());
   }
 
-  __ bind(nested_statement.break_target());
+  __ bind(nested_statement.break_label());
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
 }
 
@@ -1026,7 +1026,7 @@
   // Load the current count to a0, load the length to a1.
   __ lw(a0, MemOperand(sp, 0 * kPointerSize));
   __ lw(a1, MemOperand(sp, 1 * kPointerSize));
-  __ Branch(loop_statement.break_target(), hs, a0, Operand(a1));
+  __ Branch(loop_statement.break_label(), hs, a0, Operand(a1));
 
   // Get the current entry of the array into register a3.
   __ lw(a2, MemOperand(sp, 2 * kPointerSize));
@@ -1053,7 +1053,7 @@
   __ push(a3);  // Current entry.
   __ InvokeBuiltin(Builtins::FILTER_KEY, CALL_FUNCTION);
   __ mov(a3, result_register());
-  __ Branch(loop_statement.continue_target(), eq, a3, Operand(zero_reg));
+  __ Branch(loop_statement.continue_label(), eq, a3, Operand(zero_reg));
 
   // Update the 'each' property or variable from the possibly filtered
   // entry in register a3.
@@ -1069,7 +1069,7 @@
 
   // Generate code for the going to the next element by incrementing
   // the index (smi) stored on top of the stack.
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   __ pop(a0);
   __ Addu(a0, a0, Operand(Smi::FromInt(1)));
   __ push(a0);
@@ -1078,7 +1078,7 @@
   __ Branch(&loop);
 
   // Remove the pointers stored on the stack.
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   __ Drop(5);
 
   // Exit and decrement the loop depth.
diff --git a/src/objects.cc b/src/objects.cc
index 337dd65..1b29071 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -656,10 +656,11 @@
     }
 
     if (js_object->elements() != heap->empty_fixed_array()) {
-      MaybeObject* result = js_object->GetElementsAccessor()->GetWithReceiver(
+      MaybeObject* result = js_object->GetElementsAccessor()->Get(
+          js_object->elements(),
+          index,
           js_object,
-          receiver,
-          index);
+          receiver);
       if (result != heap->the_hole_value()) return result;
     }
   }
@@ -4466,20 +4467,6 @@
 }
 
 
-static bool HasKey(FixedArray* array, Object* key) {
-  int len0 = array->length();
-  for (int i = 0; i < len0; i++) {
-    Object* element = array->get(i);
-    if (element->IsSmi() && key->IsSmi() && (element == key)) return true;
-    if (element->IsString() &&
-        key->IsString() && String::cast(element)->Equals(String::cast(key))) {
-      return true;
-    }
-  }
-  return false;
-}
-
-
 MaybeObject* PolymorphicCodeCache::Update(MapList* maps,
                                           Code::Flags flags,
                                           Code* code) {
@@ -4641,7 +4628,7 @@
 MaybeObject* FixedArray::AddKeysFromJSArray(JSArray* array) {
   ElementsAccessor* accessor = array->GetElementsAccessor();
   MaybeObject* maybe_result =
-      accessor->AddElementsToFixedArray(array->elements(), this);
+      accessor->AddElementsToFixedArray(array->elements(), this, array, array);
   FixedArray* result;
   if (!maybe_result->To<FixedArray>(&result)) return maybe_result;
 #ifdef DEBUG
@@ -4657,55 +4644,19 @@
 
 
 MaybeObject* FixedArray::UnionOfKeys(FixedArray* other) {
-  int len0 = length();
+  ElementsAccessor* accessor = ElementsAccessor::ForArray(other);
+  MaybeObject* maybe_result =
+      accessor->AddElementsToFixedArray(other, this, NULL, NULL);
+  FixedArray* result;
+  if (!maybe_result->To<FixedArray>(&result)) return maybe_result;
 #ifdef DEBUG
   if (FLAG_enable_slow_asserts) {
-    for (int i = 0; i < len0; i++) {
-      ASSERT(get(i)->IsString() || get(i)->IsNumber());
+    for (int i = 0; i < result->length(); i++) {
+      Object* current = result->get(i);
+      ASSERT(current->IsNumber() || current->IsString());
     }
   }
 #endif
-  int len1 = other->length();
-  // Optimize if 'other' is empty.
-  // We cannot optimize if 'this' is empty, as other may have holes
-  // or non keys.
-  if (len1 == 0) return this;
-
-  // Compute how many elements are not in this.
-  int extra = 0;
-  for (int y = 0; y < len1; y++) {
-    Object* value = other->get(y);
-    if (!value->IsTheHole() && !HasKey(this, value)) extra++;
-  }
-
-  if (extra == 0) return this;
-
-  // Allocate the result
-  Object* obj;
-  { MaybeObject* maybe_obj = GetHeap()->AllocateFixedArray(len0 + extra);
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-  }
-  // Fill in the content
-  AssertNoAllocation no_gc;
-  FixedArray* result = FixedArray::cast(obj);
-  WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
-  for (int i = 0; i < len0; i++) {
-    Object* e = get(i);
-    ASSERT(e->IsString() || e->IsNumber());
-    result->set(i, e, mode);
-  }
-  // Fill in the extra keys.
-  int index = 0;
-  for (int y = 0; y < len1; y++) {
-    Object* value = other->get(y);
-    if (!value->IsTheHole() && !HasKey(this, value)) {
-      Object* e = other->get(y);
-      ASSERT(e->IsString() || e->IsNumber());
-      result->set(len0 + index, e, mode);
-      index++;
-    }
-  }
-  ASSERT(extra == index);
   return result;
 }
 
@@ -8718,9 +8669,10 @@
 
   Heap* heap = holder_handle->GetHeap();
   ElementsAccessor* handler = holder_handle->GetElementsAccessor();
-  MaybeObject* raw_result = handler->GetWithReceiver(*holder_handle,
-                                                     *this_handle,
-                                                     index);
+  MaybeObject* raw_result = handler->Get(holder_handle->elements(),
+                                         index,
+                                         *holder_handle,
+                                         *this_handle);
   if (raw_result != heap->the_hole_value()) return raw_result;
 
   RETURN_IF_SCHEDULED_EXCEPTION(isolate);
diff --git a/src/regexp.js b/src/regexp.js
index 7b851a3..a7f42d5 100644
--- a/src/regexp.js
+++ b/src/regexp.js
@@ -50,24 +50,29 @@
   var global = false;
   var ignoreCase = false;
   var multiline = false;
-
   for (var i = 0; i < flags.length; i++) {
     var c = %_CallFunction(flags, i, StringCharAt);
     switch (c) {
       case 'g':
-        // Allow duplicate flags to be consistent with JSC and others.
+        if (global) {
+          throw MakeSyntaxError("invalid_regexp_flags", [flags]);
+        }
         global = true;
         break;
       case 'i':
+        if (ignoreCase) {
+          throw MakeSyntaxError("invalid_regexp_flags", [flags]);
+        }
         ignoreCase = true;
         break;
       case 'm':
+        if (multiline) {
+          throw MakeSyntaxError("invalid_regexp_flags", [flags]);
+        }
         multiline = true;
         break;
       default:
-        // Ignore flags that have no meaning to be consistent with
-        // JSC.
-        break;
+        throw MakeSyntaxError("invalid_regexp_flags", [flags]);
     }
   }
 
diff --git a/src/scanner-base.cc b/src/scanner-base.cc
index 2ecbfd2..62eee1a 100644
--- a/src/scanner-base.cc
+++ b/src/scanner-base.cc
@@ -41,12 +41,12 @@
     : unicode_cache_(unicode_cache) { }
 
 
-uc32 Scanner::ScanHexEscape(uc32 c, int length) {
-  ASSERT(length <= 4);  // prevent overflow
+uc32 Scanner::ScanHexNumber(int expected_length) {
+  ASSERT(expected_length <= 4);  // prevent overflow
 
-  uc32 digits[4];
+  uc32 digits[4] = { 0, 0, 0, 0 };
   uc32 x = 0;
-  for (int i = 0; i < length; i++) {
+  for (int i = 0; i < expected_length; i++) {
     digits[i] = c0_;
     int d = HexValue(c0_);
     if (d < 0) {
@@ -54,12 +54,11 @@
       // should be illegal, but other JS VMs just return the
       // non-escaped version of the original character.
 
-      // Push back digits read, except the last one (in c0_).
+      // Push back digits that we have advanced past.
       for (int j = i-1; j >= 0; j--) {
         PushBack(digits[j]);
       }
-      // Notice: No handling of error - treat it as "\u"->"u".
-      return c;
+      return -1;
     }
     x = x * 16 + d;
     Advance();
@@ -640,9 +639,17 @@
     case 'n' : c = '\n'; break;
     case 'r' : c = '\r'; break;
     case 't' : c = '\t'; break;
-    case 'u' : c = ScanHexEscape(c, 4); break;
+    case 'u' : {
+      c = ScanHexNumber(4);
+      if (c < 0) c = 'u';
+      break;
+    }
     case 'v' : c = '\v'; break;
-    case 'x' : c = ScanHexEscape(c, 2); break;
+    case 'x' : {
+      c = ScanHexNumber(2);
+      if (c < 0) c = 'x';
+      break;
+    }
     case '0' :  // fall through
     case '1' :  // fall through
     case '2' :  // fall through
@@ -802,13 +809,11 @@
 
 uc32 JavaScriptScanner::ScanIdentifierUnicodeEscape() {
   Advance();
-  if (c0_ != 'u') return unibrow::Utf8::kBadChar;
+  if (c0_ != 'u') return -1;
   Advance();
-  uc32 c = ScanHexEscape('u', 4);
-  // We do not allow a unicode escape sequence to start another
-  // unicode escape sequence.
-  if (c == '\\') return unibrow::Utf8::kBadChar;
-  return c;
+  uc32 result = ScanHexNumber(4);
+  if (result < 0) PushBack('u');
+  return result;
 }
 
 
@@ -926,7 +931,11 @@
   if (c0_ == '\\') {
     uc32 c = ScanIdentifierUnicodeEscape();
     // Only allow legal identifier start characters.
-    if (!unicode_cache_->IsIdentifierStart(c)) return Token::ILLEGAL;
+    if (c < 0 ||
+        c == '\\' ||  // No recursive escapes.
+        !unicode_cache_->IsIdentifierStart(c)) {
+      return Token::ILLEGAL;
+    }
     AddLiteralChar(c);
     return ScanIdentifierSuffix(&literal);
   }
@@ -966,7 +975,11 @@
     if (c0_ == '\\') {
       uc32 c = ScanIdentifierUnicodeEscape();
       // Only allow legal identifier part characters.
-      if (!unicode_cache_->IsIdentifierPart(c)) return Token::ILLEGAL;
+      if (c < 0 ||
+          c == '\\' ||
+          !unicode_cache_->IsIdentifierPart(c)) {
+        return Token::ILLEGAL;
+      }
       AddLiteralChar(c);
     } else {
       AddLiteralChar(c0_);
@@ -992,8 +1005,9 @@
   // the scanner should pass uninterpreted bodies to the RegExp
   // constructor.
   LiteralScope literal(this);
-  if (seen_equal)
+  if (seen_equal) {
     AddLiteralChar('=');
+  }
 
   while (c0_ != '/' || in_character_class) {
     if (unicode_cache_->IsLineTerminator(c0_) || c0_ < 0) return false;
@@ -1025,20 +1039,47 @@
 }
 
 
+bool JavaScriptScanner::ScanLiteralUnicodeEscape() {
+  ASSERT(c0_ == '\\');
+  uc32 chars_read[6] = {'\\', 'u', 0, 0, 0, 0};
+  Advance();
+  int i = 1;
+  if (c0_ == 'u') {
+    i++;
+    while (i < 6) {
+      Advance();
+      if (!IsHexDigit(c0_)) break;
+      chars_read[i] = c0_;
+      i++;
+    }
+  }
+  if (i < 6) {
+    // Incomplete escape. Undo all advances and return false.
+    while (i > 0) {
+      i--;
+      PushBack(chars_read[i]);
+    }
+    return false;
+  }
+  // Complete escape. Add all chars to current literal buffer.
+  for (int i = 0; i < 6; i++) {
+    AddLiteralChar(chars_read[i]);
+  }
+  return true;
+}
+
+
 bool JavaScriptScanner::ScanRegExpFlags() {
   // Scan regular expression flags.
   LiteralScope literal(this);
   while (unicode_cache_->IsIdentifierPart(c0_)) {
-    if (c0_ == '\\') {
-      uc32 c = ScanIdentifierUnicodeEscape();
-      if (c != static_cast<uc32>(unibrow::Utf8::kBadChar)) {
-        // We allow any escaped character, unlike the restriction on
-        // IdentifierPart when it is used to build an IdentifierName.
-        AddLiteralChar(c);
-        continue;
+    if (c0_ != '\\') {
+      AddLiteralCharAdvance();
+    } else {
+      if (!ScanLiteralUnicodeEscape()) {
+        break;
       }
     }
-    AddLiteralCharAdvance();
   }
   literal.Complete();
 
diff --git a/src/scanner-base.h b/src/scanner-base.h
index 3e1772a..a7062a3 100644
--- a/src/scanner-base.h
+++ b/src/scanner-base.h
@@ -419,7 +419,7 @@
     }
   }
 
-  uc32 ScanHexEscape(uc32 c, int length);
+  uc32 ScanHexNumber(int expected_length);
 
   // Return the current source position.
   int source_pos() {
@@ -537,6 +537,10 @@
   // Decodes a unicode escape-sequence which is part of an identifier.
   // If the escape sequence cannot be decoded the result is kBadChar.
   uc32 ScanIdentifierUnicodeEscape();
+  // Recognizes a uniocde escape-sequence and adds its characters,
+  // uninterpreted, to the current literal. Used for parsing RegExp
+  // flags.
+  bool ScanLiteralUnicodeEscape();
 
   // Start position of the octal literal last scanned.
   Location octal_pos_;
diff --git a/src/spaces.h b/src/spaces.h
index d8ed27e..a0f4ba1 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -409,6 +409,7 @@
 class CodeRange {
  public:
   explicit CodeRange(Isolate* isolate);
+  ~CodeRange() { TearDown(); }
 
   // Reserves a range of virtual memory, but does not commit any of it.
   // Can only be called once, at heap initialization time.
diff --git a/src/string.js b/src/string.js
index 2a5c95e..e0f20c2 100644
--- a/src/string.js
+++ b/src/string.js
@@ -170,7 +170,7 @@
                         ["String.prototype.localeCompare"]);
   }
   if (%_ArgumentsLength() === 0) return 0;
-  return %StringLocaleCompare(TO_STRING_INLINE(this), 
+  return %StringLocaleCompare(TO_STRING_INLINE(this),
                               TO_STRING_INLINE(other));
 }
 
@@ -914,6 +914,8 @@
   this.special_string = str;
 }
 
+ReplaceResultBuilder.prototype.__proto__ = null;
+
 
 ReplaceResultBuilder.prototype.add = function(str) {
   str = TO_STRING_INLINE(str);
diff --git a/src/v8natives.js b/src/v8natives.js
index 88525f6..c16d73e 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -462,6 +462,7 @@
 }
 
 PropertyDescriptor.prototype.__proto__ = null;
+
 PropertyDescriptor.prototype.toString = function() {
   return "[object PropertyDescriptor]";
 };
@@ -1015,24 +1016,27 @@
 }
 
 
+function GetOwnEnumerablePropertyNames(properties) {
+  var names = new InternalArray();
+  for (var key in properties) {
+    if (%HasLocalProperty(properties, key)) {
+      names.push(key);
+    }
+  }
+  return names;
+}
+
+
 // ES5 section 15.2.3.7.
 function ObjectDefineProperties(obj, properties) {
   if (!IS_SPEC_OBJECT(obj))
     throw MakeTypeError("obj_ctor_property_non_object", ["defineProperties"]);
   var props = ToObject(properties);
-  var key_values = [];
-  for (var key in props) {
-    if (%HasLocalProperty(props, key)) {
-      key_values.push(key);
-      var value = props[key];
-      var desc = ToPropertyDescriptor(value);
-      key_values.push(desc);
-    }
-  }
-  for (var i = 0; i < key_values.length; i += 2) {
-    var key = key_values[i];
-    var desc = key_values[i + 1];
-    DefineOwnProperty(obj, key, desc, true);
+  var names = GetOwnEnumerablePropertyNames(props);
+  for (var i = 0; i < names.length; i++) {
+    var name = names[i];
+    var desc = ToPropertyDescriptor(props[name]);
+    DefineOwnProperty(obj, name, desc, true);
   }
   return obj;
 }
diff --git a/src/v8threads.cc b/src/v8threads.cc
index 52f82e2..3881d66 100644
--- a/src/v8threads.cc
+++ b/src/v8threads.cc
@@ -305,7 +305,9 @@
 
 
 ThreadManager::~ThreadManager() {
-  // TODO(isolates): Destroy mutexes.
+  delete mutex_;
+  delete free_anchor_;
+  delete in_use_anchor_;
 }
 
 
diff --git a/src/version.cc b/src/version.cc
index c39af56..e3cecdf 100644
--- a/src/version.cc
+++ b/src/version.cc
@@ -34,7 +34,7 @@
 // cannot be changed without changing the SCons build script.
 #define MAJOR_VERSION     3
 #define MINOR_VERSION     5
-#define BUILD_NUMBER      6
+#define BUILD_NUMBER      7
 #define PATCH_LEVEL       0
 // Use 1 for candidates and 0 otherwise.
 // (Boolean macro values are not supported by all preprocessors.)
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index d0c71be..5567df2 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -842,7 +842,7 @@
   __ bind(&next_test);
   __ Drop(1);  // Switch value is no longer needed.
   if (default_clause == NULL) {
-    __ jmp(nested_statement.break_target());
+    __ jmp(nested_statement.break_label());
   } else {
     __ jmp(default_clause->body_target());
   }
@@ -856,7 +856,7 @@
     VisitStatements(clause->statements());
   }
 
-  __ bind(nested_statement.break_target());
+  __ bind(nested_statement.break_label());
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
 }
 
@@ -982,7 +982,7 @@
   __ bind(&loop);
   __ movq(rax, Operand(rsp, 0 * kPointerSize));  // Get the current index.
   __ cmpq(rax, Operand(rsp, 1 * kPointerSize));  // Compare to the array length.
-  __ j(above_equal, loop_statement.break_target());
+  __ j(above_equal, loop_statement.break_label());
 
   // Get the current entry of the array into register rbx.
   __ movq(rbx, Operand(rsp, 2 * kPointerSize));
@@ -1010,7 +1010,7 @@
   __ push(rbx);  // Current entry.
   __ InvokeBuiltin(Builtins::FILTER_KEY, CALL_FUNCTION);
   __ Cmp(rax, Smi::FromInt(0));
-  __ j(equal, loop_statement.continue_target());
+  __ j(equal, loop_statement.continue_label());
   __ movq(rbx, rax);
 
   // Update the 'each' property or variable from the possibly filtered
@@ -1027,14 +1027,14 @@
 
   // Generate code for going to the next element by incrementing the
   // index (smi) stored on top of the stack.
-  __ bind(loop_statement.continue_target());
+  __ bind(loop_statement.continue_label());
   __ SmiAddConstant(Operand(rsp, 0 * kPointerSize), Smi::FromInt(1));
 
   EmitStackCheck(stmt);
   __ jmp(&loop);
 
   // Remove the pointers stored on the stack.
-  __ bind(loop_statement.break_target());
+  __ bind(loop_statement.break_label());
   __ addq(rsp, Immediate(5 * kPointerSize));
 
   // Exit and decrement the loop depth.
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index d5e17b8..3ed6b52 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -3617,6 +3617,52 @@
 }
 
 
+Handle<v8::Array> NonStrictArgsIndexedPropertyEnumerator(
+    const AccessorInfo& info) {
+  // Force the list of returned keys to be stored in a Arguments object.
+  Local<Script> indexed_property_names_script = Script::Compile(v8_str(
+      "function f(w,x) {"
+      " return arguments;"
+      "}"
+      "keys = f(0, 1, 2, 3);"
+      "keys;"));
+  Local<Value> result = indexed_property_names_script->Run();
+  return Local<v8::Array>(static_cast<v8::Array*>(::v8::Object::Cast(*result)));
+}
+
+
+static v8::Handle<Value> NonStrictIndexedPropertyGetter(
+    uint32_t index,
+    const AccessorInfo& info) {
+  ApiTestFuzzer::Fuzz();
+  if (index < 4) {
+    return v8::Handle<Value>(v8_num(index));
+  }
+  return v8::Handle<Value>();
+}
+
+
+// Make sure that the the interceptor code in the runtime properly handles
+// merging property name lists for non-string arguments arrays.
+THREADED_TEST(IndexedInterceptorNonStrictArgsWithIndexedAccessor) {
+  v8::HandleScope scope;
+  Local<ObjectTemplate> templ = ObjectTemplate::New();
+  templ->SetIndexedPropertyHandler(NonStrictIndexedPropertyGetter,
+                                   0,
+                                   0,
+                                   0,
+                                   NonStrictArgsIndexedPropertyEnumerator);
+  LocalContext context;
+  context->Global()->Set(v8_str("obj"), templ->NewInstance());
+  Local<Script> create_args_script =
+      Script::Compile(v8_str(
+          "var key_count = 0;"
+          "for (x in obj) {key_count++;} key_count;"));
+  Local<Value> result = create_args_script->Run();
+  CHECK_EQ(v8_num(4), result);
+}
+
+
 static v8::Handle<Value> IdentityIndexedPropertyGetter(
     uint32_t index,
     const AccessorInfo& info) {
diff --git a/test/mjsunit/regress/regress-1620.js b/test/mjsunit/regress/regress-1620.js
new file mode 100644
index 0000000..6d72974
--- /dev/null
+++ b/test/mjsunit/regress/regress-1620.js
@@ -0,0 +1,54 @@
+// Copyright 2011 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.
+
+// Don't allow malformed unicode escape sequences in identifiers.
+// In strings and regexps we currently allow malformed unicode escape
+// sequences without throwing a SyntaxError. Instead "\u22gk" would
+// treat the "\u" as an identity escape, and evaluate to "u22gk".
+// Due to code sharing, we did the same in identifiers. This should
+// no longer be the case.
+// See: http://code.google.com/p/v8/issues/detail?id=1620
+
+assertThrows("var \\u\\u\\u = 42;");
+assertThrows("var \\u41 = 42;");
+assertThrows("var \\u123 = 42;");
+eval("var \\u1234 = 42;");
+assertEquals(42, eval("\u1234"));
+assertThrows("var uuu = 42; var x = \\u\\u\\u");
+
+// Regressions introduced and fixed again while fixing the above.
+
+// Handle 0xFFFD correctly (it's a valid value, and shouldn't be used
+// to mark an error).
+assertEquals(0xFFFD, "\uFFFD".charCodeAt(0));
+
+// Handle unicode escapes in regexp flags correctly.
+assertThrows("/x/g\\uim", SyntaxError);
+assertThrows("/x/g\\u2im", SyntaxError);
+assertThrows("/x/g\\u22im", SyntaxError);
+assertThrows("/x/g\\u222im", SyntaxError);
+assertThrows("/x/g\\\\u2222im", SyntaxError);
diff --git a/test/mjsunit/regress/regress-1625.js b/test/mjsunit/regress/regress-1625.js
new file mode 100644
index 0000000..a2ef8df
--- /dev/null
+++ b/test/mjsunit/regress/regress-1625.js
@@ -0,0 +1,36 @@
+// Copyright 2011 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.
+
+// Test that overwriting Array.prototype.push does not make
+// Object.defineProperties misbehave.
+
+Array.prototype.push = 1;
+var desc = {foo: {value: 10}, bar: {get: function() {return 42; }}};
+var obj = {};
+var x = Object.defineProperties(obj, desc);
+assertEquals(x.foo, 10);
+assertEquals(x.bar, 42);
diff --git a/test/mjsunit/regress/regress-219.js b/test/mjsunit/regress/regress-219.js
index 4bfabdc..b751f0f 100644
--- a/test/mjsunit/regress/regress-219.js
+++ b/test/mjsunit/regress/regress-219.js
@@ -30,6 +30,10 @@
 // We should now allow duplicates of flags.
 // (See http://code.google.com/p/v8/issues/detail?id=219)
 
+// This has been reversed by issue 1628, since other browsers have also
+// tightened their syntax.
+// (See http://code.google.com/p/v8/issues/detail?id=1628)
+
 // Base tests: we recognize the basic flags
 
 function assertFlags(re, global, multiline, ignoreCase) {
@@ -53,124 +57,92 @@
 
 // Double i's
 
-re = /a/ii;
-assertFlags(re, false, false, true)
+assertThrows("/a/ii");
 
-re = /a/gii;
-assertFlags(re, true, false, true)
+assertThrows("/a/gii");
 
-re = /a/igi;
-assertFlags(re, true, false, true)
+assertThrows("/a/igi");
 
-re = /a/iig;
-assertFlags(re, true, false, true)
+assertThrows("/a/iig");
 
-re = /a/gimi;
-assertFlags(re, true, true, true)
+assertThrows("/a/gimi");
 
-re = /a/giim;
-assertFlags(re, true, true, true)
+assertThrows("/a/giim");
 
-re = /a/igim;
-assertFlags(re, true, true, true)
+assertThrows("/a/igim");
 
+assertThrows(function(){ return RegExp("a", "ii"); })
 
-re = RegExp("a", "ii");
-assertFlags(re, false, false, true)
+assertThrows(function(){ return RegExp("a", "gii"); })
 
-re = RegExp("a", "gii");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "igi"); })
 
-re = RegExp("a", "igi");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "iig"); })
 
-re = RegExp("a", "iig");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "gimi"); })
 
-re = RegExp("a", "gimi");
-assertFlags(re, true, true, true)
+assertThrows(function(){ return RegExp("a", "giim"); })
 
-re = RegExp("a", "giim");
-assertFlags(re, true, true, true)
-
-re = RegExp("a", "igim");
-assertFlags(re, true, true, true)
+assertThrows(function(){ return RegExp("a", "igim"); })
 
 // Tripple i's
 
-re = /a/iii;
-assertFlags(re, false, false, true)
+assertThrows("/a/iii");
 
-re = /a/giii;
-assertFlags(re, true, false, true)
+assertThrows("/a/giii");
 
-re = /a/igii;
-assertFlags(re, true, false, true)
+assertThrows("/a/igii");
 
-re = /a/iigi;
-assertFlags(re, true, false, true)
+assertThrows("/a/iigi");
 
-re = /a/iiig;
-assertFlags(re, true, false, true)
+assertThrows("/a/iiig");
 
-re = /a/miiig;
-assertFlags(re, true, true, true)
+assertThrows("/a/miiig");
 
+assertThrows(function(){ return RegExp("a", "iii"); })
 
-re = RegExp("a", "iii");
-assertFlags(re, false, false, true)
+assertThrows(function(){ return RegExp("a", "giii"); })
 
-re = RegExp("a", "giii");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "igii"); })
 
-re = RegExp("a", "igii");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "iigi"); })
 
-re = RegExp("a", "iigi");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "iiig"); })
 
-re = RegExp("a", "iiig");
-assertFlags(re, true, false, true)
+assertThrows(function(){ return RegExp("a", "miiig"); })
 
-re = RegExp("a", "miiig");
-assertFlags(re, true, true, true)
+// Illegal flags - valid flags late in string.
 
-// Illegal flags - flags late in string.
+assertThrows("/a/arglebargleglopglyf");
 
-re = /a/arglebargleglopglyf;
-assertFlags(re, true, false, false)
+assertThrows("/a/arglebargleglopglif");
 
-re = /a/arglebargleglopglif;
-assertFlags(re, true, false, true)
+assertThrows("/a/arglebargleglopglym");
 
-re = /a/arglebargleglopglym;
-assertFlags(re, true, true, false)
-
-re = /a/arglebargleglopglim;
-assertFlags(re, true, true, true)
+assertThrows("/a/arglebargleglopglim");
 
 // Case of flags still matters.
 
-re = /a/gmi;
+var re = /a/gmi;
 assertFlags(re, true, true, true)
 
-re = /a/Gmi;
-assertFlags(re, false, true, true)
+assertThrows("/a/Gmi");
 
-re = /a/gMi;
-assertFlags(re, true, false, true)
+assertThrows("/a/gMi");
 
-re = /a/gmI;
-assertFlags(re, true, true, false)
+assertThrows("/a/gmI");
 
-re = /a/GMi;
-assertFlags(re, false, false, true)
+assertThrows("/a/GMi");
 
-re = /a/GmI;
-assertFlags(re, false, true, false)
+assertThrows("/a/GmI");
 
-re = /a/gMI;
-assertFlags(re, true, false, false)
+assertThrows("/a/gMI");
 
-re = /a/GMI;
-assertFlags(re, false, false, false)
+assertThrows("/a/GMI");
+
+// Unicode escape sequences are not interpreted.
+
+assertThrows("/a/\\u0067");
+assertThrows("/a/\\u0069");
+assertThrows("/a/\\u006d");
+assertThrows("/a/\\u006D");
diff --git a/test/mjsunit/regress/regress-87.js b/test/mjsunit/regress/regress-87.js
index 131cb58..10446fd 100644
--- a/test/mjsunit/regress/regress-87.js
+++ b/test/mjsunit/regress/regress-87.js
@@ -25,34 +25,29 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-function testFlags(flagstring, global, ignoreCase, multiline) {
-  var text = "/x/"+flagstring;
-  var re = eval(text);
-  assertEquals(global, re.global, text + ".global");
-  assertEquals(ignoreCase, re.ignoreCase, text + ".ignoreCase");
-  assertEquals(multiline, re.multiline, text + ".multiline");
-}
+// In Issue 87, we allowed unicode escape sequences in RegExp flags.
+// However, according to ES5, they should not be interpreted, but passed
+// verbatim to the RegExp constructor.
+// (On top of that, the original test was bugged and never tested anything).
+// The behavior was changed in r8969 to not interpret escapes, but this
+// test didn't test that, and only failed when making invalid flag characters
+// an error too.
 
-testFlags("", false, false, false);
+assertThrows("/x/\\u0067");
+assertThrows("/x/\\u0069");
+assertThrows("/x/\\u006d");
 
-testFlags("\u0067", true, false, false);
+assertThrows("/x/\\u0067i");
+assertThrows("/x/\\u0069m");
+assertThrows("/x/\\u006dg");
 
-testFlags("\u0069", false, true, false)
+assertThrows("/x/m\\u0067");
+assertThrows("/x/g\\u0069");
+assertThrows("/x/i\\u006d");
 
-testFlags("\u006d", false, false, true);
+assertThrows("/x/m\\u0067i");
+assertThrows("/x/g\\u0069m");
+assertThrows("/x/i\\u006dg");
 
-testFlags("\u0068", false, false, false);
-
-testFlags("\u0020", false, false, false);
-
-
-testFlags("\u0067g", true, false, false);
-
-testFlags("g\u0067", true, false, false);
-
-testFlags("abc\u0067efg", true, false, false);
-
-testFlags("i\u0067", true, true, false);
-
-testFlags("\u0067i", true, true, false);
-
+assertThrows("/x/\\u0068");
+assertThrows("/x/\\u0020");
diff --git a/test/mozilla/mozilla.status b/test/mozilla/mozilla.status
index c62d770..f6d6925 100644
--- a/test/mozilla/mozilla.status
+++ b/test/mozilla/mozilla.status
@@ -246,9 +246,8 @@
 ecma_3/Number/15.7.4.6-1: FAIL_OK
 
 #:=== RegExp:=== 
-# To be compatible with JSC we silently ignore flags that do not make
-# sense.  These tests expects us to throw exceptions.  
-ecma_3/RegExp/regress-57631: FAIL_OK
+# We don't match the syntax error message of Mozilla for invalid
+# RegExp flags.
 ecma_3/RegExp/15.10.4.1-6: FAIL_OK
 
 # PCRE doesn't allow subpattern nesting deeper than 200, this tests
diff --git a/test/sputnik/sputnik.status b/test/sputnik/sputnik.status
index 82d8a61..868509d 100644
--- a/test/sputnik/sputnik.status
+++ b/test/sputnik/sputnik.status
@@ -56,15 +56,6 @@
 # errors, for compatibility.
 S15.10.2.11_A1_T2: FAIL
 S15.10.2.11_A1_T3: FAIL
-S15.10.4.1_A5_T1: FAIL
-S15.10.4.1_A5_T2: FAIL
-S15.10.4.1_A5_T3: FAIL
-S15.10.4.1_A5_T4: FAIL
-S15.10.4.1_A5_T5: FAIL
-S15.10.4.1_A5_T6: FAIL
-S15.10.4.1_A5_T7: FAIL
-S15.10.4.1_A5_T8: FAIL
-S15.10.4.1_A5_T9: FAIL
 
 # We are more lenient in which string character escapes we allow than
 # the spec (7.8.4 p. 19) wants us to be.  This is for compatibility.
@@ -99,6 +90,13 @@
 S7.8.4_A4.3_T5: FAIL_OK
 S7.8.4_A7.2_T5: FAIL_OK
 
+# Sputnik expects unicode escape sequences in RegExp flags to be interpreted.
+# The specification requires them to be passed uninterpreted to the RegExp
+# constructor. We now implement that.
+S7.8.5_A3.1_T7: FAIL_OK
+S7.8.5_A3.1_T8: FAIL_OK
+S7.8.5_A3.1_T9: FAIL_OK
+
 # We allow some keywords to be used as identifiers.
 S7.5.3_A1.15: FAIL_OK
 S7.5.3_A1.18: FAIL_OK
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index 0397246..97dc392 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -144,7 +144,6 @@
           'Debug': {
             'defines': [
               'DEBUG',
-              '_DEBUG',
               'ENABLE_DISASSEMBLER',
               'V8_ENABLE_CHECKS',
               'OBJECT_PRINT',
@@ -372,7 +371,10 @@
                 '<(INTERMEDIATE_DIR)/snapshot.cc',
               ],
               'variables': {
-                'mksnapshot_flags': [],
+                'mksnapshot_flags': [
+                  '--log-snapshot-positions',
+                  '--logfile', '<(INTERMEDIATE_DIR)/snapshot.log',
+                ],
               },
               'conditions': [
                 ['v8_target_arch=="arm"', {