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

Source/heap/Heap.h

Index: Source/heap/Heap.h
diff --git a/Source/heap/Heap.h b/Source/heap/Heap.h
index 8e59b282ccba646aaba34729cd57304048e120b3..d4f4a4d7e7832f4674ec6b35e51138174045ad67 100644
--- a/Source/heap/Heap.h
+++ b/Source/heap/Heap.h
@@ -779,7 +779,7 @@ public:
     // on a static callback stack and the weak callback is performed
     // on the thread performing garbage collection. This is OK because
     // cells are just cleared and no deallocation can happen.
-    static void pushWeakObjectPointerCallback(void* containerObject, WeakPointerCallback);
+    static void pushWeakObjectPointerCallback(void* closure, void* containerObject, WeakPointerCallback);

[Mads Ager (chromium), 2014/03/12 15:46:50]

Please update the comment with an explanation of what decided the thread and
what gets the callback. We might want to rename containerObject here?

Also, maybe add a comment that closure and object are usually the same but that
for heap collections, they are different because the front object needs to get
the callback but the backing store is the only thing that is guaranteed to be in
the heap.

[Erik Corry, 2014/03/13 07:46:21]

Done.

     static void pushWeakCellPointerCallback(void** cell, WeakPointerCallback);
 
     // Pop the top of the marking stack and call the callback with the visitor
@@ -1263,9 +1263,9 @@ public:
         return hasDeadMember(visitor, t.key) || hasDeadMember(visitor, t.value);
     }
 
-    static void registerWeakMembers(Visitor* visitor, const void* object, WeakPointerCallback callback)
+    static void registerWeakMembers(Visitor* visitor, const void* closure, const void* object, WeakPointerCallback callback)
     {
-        visitor->registerWeakMembers(object, callback);
+        visitor->registerWeakMembers(closure, object, callback);
     }
 
     template<typename T>