diff --git a/src/runtime/runtime-collections.cc b/src/runtime/runtime-collections.cc
index abdd056..32340e5 100644
--- a/src/runtime/runtime-collections.cc
+++ b/src/runtime/runtime-collections.cc
@@ -2,57 +2,77 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "src/v8.h"
-
-#include "src/arguments.h"
 #include "src/runtime/runtime-utils.h"
 
+#include "src/arguments.h"
+#include "src/conversions-inl.h"
+#include "src/factory.h"
 
 namespace v8 {
 namespace internal {
 
+
+RUNTIME_FUNCTION(Runtime_StringGetRawHashField) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(String, string, 0);
+  return *isolate->factory()->NewNumberFromUint(string->hash_field());
+}
+
+
+RUNTIME_FUNCTION(Runtime_TheHole) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 0);
+  return isolate->heap()->the_hole_value();
+}
+
+
+RUNTIME_FUNCTION(Runtime_JSCollectionGetTable) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_CHECKED(JSObject, object, 0);
+  RUNTIME_ASSERT(object->IsJSSet() || object->IsJSMap());
+  return static_cast<JSCollection*>(object)->table();
+}
+
+
+RUNTIME_FUNCTION(Runtime_GenericHash) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
+  Handle<Smi> hash = Object::GetOrCreateHash(isolate, object);
+  return *hash;
+}
+
+
 RUNTIME_FUNCTION(Runtime_SetInitialize) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
-  Handle<OrderedHashSet> table = isolate->factory()->NewOrderedHashSet();
-  holder->set_table(*table);
+  JSSet::Initialize(holder, isolate);
   return *holder;
 }
 
 
-RUNTIME_FUNCTION(Runtime_SetAdd) {
+RUNTIME_FUNCTION(Runtime_SetGrow) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
   Handle<OrderedHashSet> table(OrderedHashSet::cast(holder->table()));
-  table = OrderedHashSet::Add(table, key);
+  table = OrderedHashSet::EnsureGrowable(table);
   holder->set_table(*table);
-  return *holder;
+  return isolate->heap()->undefined_value();
 }
 
 
-RUNTIME_FUNCTION(Runtime_SetHas) {
+RUNTIME_FUNCTION(Runtime_SetShrink) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
   Handle<OrderedHashSet> table(OrderedHashSet::cast(holder->table()));
-  return isolate->heap()->ToBoolean(table->Contains(key));
-}
-
-
-RUNTIME_FUNCTION(Runtime_SetDelete) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
-  Handle<OrderedHashSet> table(OrderedHashSet::cast(holder->table()));
-  bool was_present = false;
-  table = OrderedHashSet::Remove(table, key, &was_present);
+  table = OrderedHashSet::Shrink(table);
   holder->set_table(*table);
-  return isolate->heap()->ToBoolean(was_present);
+  return isolate->heap()->undefined_value();
 }
 
 
@@ -60,22 +80,11 @@
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
-  Handle<OrderedHashSet> table(OrderedHashSet::cast(holder->table()));
-  table = OrderedHashSet::Clear(table);
-  holder->set_table(*table);
+  JSSet::Clear(holder);
   return isolate->heap()->undefined_value();
 }
 
 
-RUNTIME_FUNCTION(Runtime_SetGetSize) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 1);
-  CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
-  Handle<OrderedHashSet> table(OrderedHashSet::cast(holder->table()));
-  return Smi::FromInt(table->NumberOfElements());
-}
-
-
 RUNTIME_FUNCTION(Runtime_SetIteratorInitialize) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
@@ -135,45 +144,19 @@
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
-  Handle<OrderedHashMap> table = isolate->factory()->NewOrderedHashMap();
-  holder->set_table(*table);
+  JSMap::Initialize(holder, isolate);
   return *holder;
 }
 
 
-RUNTIME_FUNCTION(Runtime_MapGet) {
+RUNTIME_FUNCTION(Runtime_MapShrink) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
   Handle<OrderedHashMap> table(OrderedHashMap::cast(holder->table()));
-  Handle<Object> lookup(table->Lookup(key), isolate);
-  return lookup->IsTheHole() ? isolate->heap()->undefined_value() : *lookup;
-}
-
-
-RUNTIME_FUNCTION(Runtime_MapHas) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
-  Handle<OrderedHashMap> table(OrderedHashMap::cast(holder->table()));
-  Handle<Object> lookup(table->Lookup(key), isolate);
-  return isolate->heap()->ToBoolean(!lookup->IsTheHole());
-}
-
-
-RUNTIME_FUNCTION(Runtime_MapDelete) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
-  Handle<OrderedHashMap> table(OrderedHashMap::cast(holder->table()));
-  bool was_present = false;
-  Handle<OrderedHashMap> new_table =
-      OrderedHashMap::Remove(table, key, &was_present);
-  holder->set_table(*new_table);
-  return isolate->heap()->ToBoolean(was_present);
+  table = OrderedHashMap::Shrink(table);
+  holder->set_table(*table);
+  return isolate->heap()->undefined_value();
 }
 
 
@@ -181,32 +164,19 @@
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
-  Handle<OrderedHashMap> table(OrderedHashMap::cast(holder->table()));
-  table = OrderedHashMap::Clear(table);
-  holder->set_table(*table);
+  JSMap::Clear(holder);
   return isolate->heap()->undefined_value();
 }
 
 
-RUNTIME_FUNCTION(Runtime_MapSet) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 3);
-  CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
-  CONVERT_ARG_HANDLE_CHECKED(Object, value, 2);
-  Handle<OrderedHashMap> table(OrderedHashMap::cast(holder->table()));
-  Handle<OrderedHashMap> new_table = OrderedHashMap::Put(table, key, value);
-  holder->set_table(*new_table);
-  return *holder;
-}
-
-
-RUNTIME_FUNCTION(Runtime_MapGetSize) {
+RUNTIME_FUNCTION(Runtime_MapGrow) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
   Handle<OrderedHashMap> table(OrderedHashMap::cast(holder->table()));
-  return Smi::FromInt(table->NumberOfElements());
+  table = OrderedHashMap::EnsureGrowable(table);
+  holder->set_table(*table);
+  return isolate->heap()->undefined_value();
 }
 
 
@@ -270,6 +240,11 @@
   }
   Handle<FixedArray> entries =
       isolate->factory()->NewFixedArray(max_entries * 2);
+  // Allocation can cause GC can delete weak elements. Reload.
+  if (max_entries > table->NumberOfElements()) {
+    max_entries = table->NumberOfElements();
+  }
+
   {
     DisallowHeapAllocation no_gc;
     int count = 0;
@@ -296,88 +271,72 @@
 }
 
 
-static Handle<JSWeakCollection> WeakCollectionInitialize(
-    Isolate* isolate, Handle<JSWeakCollection> weak_collection) {
-  DCHECK(weak_collection->map()->inobject_properties() == 0);
-  Handle<ObjectHashTable> table = ObjectHashTable::New(isolate, 0);
-  weak_collection->set_table(*table);
-  return weak_collection;
-}
-
-
 RUNTIME_FUNCTION(Runtime_WeakCollectionInitialize) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSWeakCollection, weak_collection, 0);
-  return *WeakCollectionInitialize(isolate, weak_collection);
+  JSWeakCollection::Initialize(weak_collection, isolate);
+  return *weak_collection;
 }
 
 
 RUNTIME_FUNCTION(Runtime_WeakCollectionGet) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSWeakCollection, weak_collection, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
+  CONVERT_SMI_ARG_CHECKED(hash, 2)
   RUNTIME_ASSERT(key->IsJSReceiver() || key->IsSymbol());
   Handle<ObjectHashTable> table(
       ObjectHashTable::cast(weak_collection->table()));
   RUNTIME_ASSERT(table->IsKey(*key));
-  Handle<Object> lookup(table->Lookup(key), isolate);
+  Handle<Object> lookup(table->Lookup(key, hash), isolate);
   return lookup->IsTheHole() ? isolate->heap()->undefined_value() : *lookup;
 }
 
 
 RUNTIME_FUNCTION(Runtime_WeakCollectionHas) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSWeakCollection, weak_collection, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
+  CONVERT_SMI_ARG_CHECKED(hash, 2)
   RUNTIME_ASSERT(key->IsJSReceiver() || key->IsSymbol());
   Handle<ObjectHashTable> table(
       ObjectHashTable::cast(weak_collection->table()));
   RUNTIME_ASSERT(table->IsKey(*key));
-  Handle<Object> lookup(table->Lookup(key), isolate);
+  Handle<Object> lookup(table->Lookup(key, hash), isolate);
   return isolate->heap()->ToBoolean(!lookup->IsTheHole());
 }
 
 
 RUNTIME_FUNCTION(Runtime_WeakCollectionDelete) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSWeakCollection, weak_collection, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
+  CONVERT_SMI_ARG_CHECKED(hash, 2)
   RUNTIME_ASSERT(key->IsJSReceiver() || key->IsSymbol());
   Handle<ObjectHashTable> table(
       ObjectHashTable::cast(weak_collection->table()));
   RUNTIME_ASSERT(table->IsKey(*key));
-  bool was_present = false;
-  Handle<ObjectHashTable> new_table =
-      ObjectHashTable::Remove(table, key, &was_present);
-  weak_collection->set_table(*new_table);
-  if (*table != *new_table) {
-    // Zap the old table since we didn't record slots for its elements.
-    table->FillWithHoles(0, table->length());
-  }
+  bool was_present = JSWeakCollection::Delete(weak_collection, key, hash);
   return isolate->heap()->ToBoolean(was_present);
 }
 
 
 RUNTIME_FUNCTION(Runtime_WeakCollectionSet) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 3);
+  DCHECK(args.length() == 4);
   CONVERT_ARG_HANDLE_CHECKED(JSWeakCollection, weak_collection, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
   RUNTIME_ASSERT(key->IsJSReceiver() || key->IsSymbol());
   CONVERT_ARG_HANDLE_CHECKED(Object, value, 2);
+  CONVERT_SMI_ARG_CHECKED(hash, 3)
   Handle<ObjectHashTable> table(
       ObjectHashTable::cast(weak_collection->table()));
   RUNTIME_ASSERT(table->IsKey(*key));
-  Handle<ObjectHashTable> new_table = ObjectHashTable::Put(table, key, value);
-  weak_collection->set_table(*new_table);
-  if (*table != *new_table) {
-    // Zap the old table since we didn't record slots for its elements.
-    table->FillWithHoles(0, table->length());
-  }
+  JSWeakCollection::Set(weak_collection, key, value, hash);
   return *weak_collection;
 }
 
@@ -414,14 +373,9 @@
 RUNTIME_FUNCTION(Runtime_ObservationWeakMapCreate) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 0);
-  // TODO(adamk): Currently this runtime function is only called three times per
-  // isolate. If it's called more often, the map should be moved into the
-  // strong root list.
-  Handle<Map> map =
-      isolate->factory()->NewMap(JS_WEAK_MAP_TYPE, JSWeakMap::kSize);
-  Handle<JSWeakMap> weakmap =
-      Handle<JSWeakMap>::cast(isolate->factory()->NewJSObjectFromMap(map));
-  return *WeakCollectionInitialize(isolate, weakmap);
+  Handle<JSWeakMap> weakmap = isolate->factory()->NewJSWeakMap();
+  JSWeakCollection::Initialize(weakmap, isolate);
+  return *weakmap;
 }
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8