Bugfix: AllocationSite objects need to be walkable by the heap snapshot

src/heap-snapshot-generator.h

 // Copyright 2013 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 442 matching lines @@
   void ExtractContextReferences(int entry, Context* context);
   void ExtractMapReferences(int entry, Map* map);
   void ExtractSharedFunctionInfoReferences(int entry,
                                            SharedFunctionInfo* shared);
   void ExtractScriptReferences(int entry, Script* script);
   void ExtractAccessorPairReferences(int entry, AccessorPair* accessors);
   void ExtractCodeCacheReferences(int entry, CodeCache* code_cache);
   void ExtractCodeReferences(int entry, Code* code);
   void ExtractCellReferences(int entry, Cell* cell);
   void ExtractPropertyCellReferences(int entry, PropertyCell* cell);
+  void ExtractAllocationSiteReferences(int entry, AllocationSite* site);
   void ExtractClosureReferences(JSObject* js_obj, int entry);
   void ExtractPropertyReferences(JSObject* js_obj, int entry);
   bool ExtractAccessorPairProperty(JSObject* js_obj, int entry,
                                    Object* key, Object* callback_obj);
   void ExtractElementReferences(JSObject* js_obj, int entry);
   void ExtractInternalReferences(JSObject* js_obj, int entry);
   bool IsEssentialObject(Object* object);
   void SetContextReference(HeapObject* parent_obj,
                            int parent,
                            String* reference_name,
@@ skipping 204 matching lines @@
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_SNAPSHOT_GENERATOR_H_