v8binding: Makes WindowProxy::global_proxy_ a weak reference when detached.

third_party/WebKit/Source/bindings/core/v8/RemoteWindowProxy.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 Google Inc. 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
@@ skipping 48 matching lines @@
   if (next_status == Lifecycle::kGlobalObjectIsDetached &&
       !global_proxy_.IsEmpty()) {
     global_proxy_.Get().SetWrapperClassId(0);
     V8DOMWrapper::ClearNativeInfo(GetIsolate(),
                                   global_proxy_.NewLocal(GetIsolate()));
 #if DCHECK_IS_ON()
     DidDetachGlobalObject();
 #endif
   }
 
+  if (next_status == Lifecycle::kFrameIsDetached) {
+    // The context's frame is detached from the DOM, so there shouldn't be a
+    // strong reference to the context.
+    global_proxy_.SetPhantom();
+  }
+
   DCHECK_EQ(lifecycle_, Lifecycle::kContextIsInitialized);
   lifecycle_ = next_status;
 }
 
 void RemoteWindowProxy::Initialize() {
   TRACE_EVENT1("v8", "RemoteWindowProxy::initialize", "isMainWindow",
                GetFrame()->IsMainFrame());
   SCOPED_BLINK_UMA_HISTOGRAM_TIMER(
       GetFrame()->IsMainFrame()
           ? "Blink.Binding.InitializeMainRemoteWindowProxy"
@@ skipping 49 matching lines @@
 
   // The global object, aka window wrapper object.
   v8::Local<v8::Object> window_wrapper =
       global_proxy->GetPrototype().As<v8::Object>();
   v8::Local<v8::Object> associated_wrapper =
       AssociateWithWrapper(window, wrapper_type_info, window_wrapper);
   DCHECK(associated_wrapper == window_wrapper);
 }
 
 }  // namespace blink