add weakcallback without persistent copying

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 631 matching lines @@
 RUNTIME_FUNCTION(MaybeObject*, Runtime_Fix) {
   NoHandleAllocation ha(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_CHECKED(JSProxy, proxy, 0);
   proxy->Fix();
   return isolate->heap()->undefined_value();
 }
 
 
 static void ArrayBufferWeakCallback(v8::Isolate* external_isolate,
-                                    Persistent<Value> object,
+                                    Persistent<Value>* object,
                                     void* data) {
   Isolate* isolate = reinterpret_cast<Isolate*>(external_isolate);
   HandleScope scope(isolate);
-  Handle<Object> internal_object = Utils::OpenHandle(*object);
+  Handle<Object> internal_object = Utils::OpenHandle(**object);
 
   size_t allocated_length = NumberToSize(
       isolate, JSArrayBuffer::cast(*internal_object)->byte_length());
   isolate->heap()->AdjustAmountOfExternalAllocatedMemory(
       -static_cast<intptr_t>(allocated_length));
   if (data != NULL)
     free(data);
-  object.Dispose(external_isolate);
+  object->Dispose(external_isolate);
 }
 
 
 bool Runtime::SetupArrayBuffer(Isolate* isolate,
                                Handle<JSArrayBuffer> array_buffer,
                                void* data,
                                size_t allocated_length) {
   array_buffer->set_backing_store(data);
 
   Handle<Object> byte_length =
@@ skipping 12706 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal