Reintroduced dictionary that can use objects as keys.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 53a3183694cbfdfc87f16524888036e27d434d14..34b7c2e229c457c7212514c3f1856094000c966d 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -4252,6 +4252,11 @@ MaybeObject* JSObject::SetHiddenPropertiesObject(Object* hidden_obj) {
 }
 
 
+bool JSObject::HasHiddenProperties() {
+  return !GetHiddenProperties(OMIT_CREATION)->ToObjectChecked()->IsUndefined();
+}
+
+
 bool JSObject::HasElement(uint32_t index) {
   return HasElementWithReceiver(this, index);
 }
@@ -4367,6 +4372,31 @@ MaybeObject* StringDictionaryShape::AsObject(String* key) {
 }
 
 
+bool ObjectHashTableShape::IsMatch(JSObject* key, Object* other) {
+  return key == JSObject::cast(other);
+}
+
+
+uint32_t ObjectHashTableShape::Hash(JSObject* key) {
+  MaybeObject* maybe_hash = key->GetIdentityHash(JSObject::OMIT_CREATION);
+  ASSERT(!maybe_hash->IsFailure());
+  return Smi::cast(maybe_hash->ToObjectUnchecked())->value();
+}
+
+
+uint32_t ObjectHashTableShape::HashForObject(JSObject* key, Object* other) {
+  MaybeObject* maybe_hash = JSObject::cast(other)->GetIdentityHash(
+      JSObject::OMIT_CREATION);
+  ASSERT(!maybe_hash->IsFailure());
+  return Smi::cast(maybe_hash->ToObjectUnchecked())->value();
+}
+
+
+MaybeObject* ObjectHashTableShape::AsObject(JSObject* key) {
+  return key;
+}
+
+
 void Map::ClearCodeCache(Heap* heap) {
   // No write barrier is needed since empty_fixed_array is not in new space.
   // Please note this function is used during marking: