Thread-local weak processing should just use a global weak callback stacks

third_party/WebKit/Source/platform/heap/Heap.cpp

Index: third_party/WebKit/Source/platform/heap/Heap.cpp
diff --git a/third_party/WebKit/Source/platform/heap/Heap.cpp b/third_party/WebKit/Source/platform/heap/Heap.cpp
index c35427805c97a2dc9e2db72ebea7fbfa64182bd2..7d17740fb56c7733274b6a036c0116549111fb1a 100644
--- a/third_party/WebKit/Source/platform/heap/Heap.cpp
+++ b/third_party/WebKit/Source/platform/heap/Heap.cpp
@@ -314,8 +314,8 @@ void ThreadHeap::pushThreadLocalWeakCallback(void* closure,
                                              WeakCallback callback) {
   ASSERT(ThreadState::current()->isInGC());
 
-  ThreadState* state = pageFromObject(object)->arena()->getThreadState();
-  state->pushThreadLocalWeakCallback(closure, callback);
+  CallbackStack::Item* slot = m_globalWeakCallbackStack->allocateEntry();
+  *slot = CallbackStack::Item(closure, callback);
 }
 
 bool ThreadHeap::popAndInvokeGlobalWeakCallback(Visitor* visitor) {