Make object groups and implicit references a bit more lightweight.

src/api.cc

 // Copyright 2010 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
@@ skipping 4455 matching lines @@
 }
 
 
 void V8::AddImplicitReferences(Persistent<Object> parent,
                                Persistent<Value>* children,
                                size_t length) {
   i::Isolate* isolate = i::Isolate::Current();
   if (IsDeadCheck(isolate, "v8::V8::AddImplicitReferences()")) return;
   STATIC_ASSERT(sizeof(Persistent<Value>) == sizeof(i::Object**));
   isolate->global_handles()->AddImplicitReferences(
-      *Utils::OpenHandle(*parent),
+      i::Handle<i::HeapObject>::cast(Utils::OpenHandle(*parent)).location(),
       reinterpret_cast<i::Object***>(children), length);
 }
 
 
 int V8::AdjustAmountOfExternalAllocatedMemory(int change_in_bytes) {
   i::Isolate* isolate = i::Isolate::Current();
   if (IsDeadCheck(isolate, "v8::V8::AdjustAmountOfExternalAllocatedMemory()")) {
     return 0;
   }
   return isolate->heap()->AdjustAmountOfExternalAllocatedMemory(
@@ skipping 1182 matching lines @@
 
 
 char* HandleScopeImplementer::Iterate(ObjectVisitor* v, char* storage) {
   HandleScopeImplementer* scope_implementer =
       reinterpret_cast<HandleScopeImplementer*>(storage);
   scope_implementer->IterateThis(v);
   return storage + ArchiveSpacePerThread();
 }
 
 } }  // namespace v8::internal