Fix PersistentHeapHashMap to work with stack allocated, heap backed weak collections

Source/heap/Visitor.h

 /*
  * Copyright (C) 2013 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 321 matching lines @@
     // HeapHashMap can cause an allocation if the backing store resizes, but
     // these collections know to remove WeakMember elements safely.
     //
     // The weak pointer callbacks are run on the thread that owns the
     // object and other threads are not stopped during the
     // callbacks. Since isAlive is used in the callback to determine
     // if objects pointed to are alive it is crucial that the object
     // pointed to belong to the same thread as the object receiving
     // the weak callback. Since other threads have been resumed the
     // mark bits are not valid for objects from other threads.
-    virtual void registerWeakMembers(const void*, WeakPointerCallback) = 0;
+    virtual void registerWeakMembers(const void* object, WeakPointerCallback callback) { registerWeakMembers(object, object, callback); }
+    virtual void registerWeakMembers(const void*, const void*, WeakPointerCallback) = 0;
 
     template<typename T, void (T::*method)(Visitor*)>
     void registerWeakMembers(const T* obj)
     {
         registerWeakMembers(obj, &TraceMethodDelegate<T, method>::trampoline);
     }
 
     // For simple cases where you just want to zero out a cell when the thing
     // it is pointing at is garbage, you can use this. This will register a
     // callback for each cell that needs to be zeroed, so if you have a lot of
@@ skipping 303 matching lines @@
 struct GCInfoTrait {
     static const GCInfo* get()
     {
         return GCInfoAtBase<typename GetGarbageCollectedBase<T>::type>::get();
     }
 };
 
 }
 
 #endif