Serialize edge counts instead of indexes in heap snapshot.

src/profile-generator.h

 // Copyright 2011 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 1054 matching lines @@
   INLINE(static uint32_t ObjectHash(const void* key)) {
     return ComputeIntegerHash(
         static_cast<uint32_t>(reinterpret_cast<uintptr_t>(key)),
         v8::internal::kZeroHashSeed);
   }
 
   HeapSnapshot* CreateFakeSnapshot();
   int GetStringId(const char* s);
   int entry_index(HeapEntry* e) { return e->index() * kNodeFieldsCount; }
   void SerializeEdge(HeapGraphEdge* edge, bool first_edge);
-  void SerializeEdges(const List<HeapEntry>& nodes);
+  void SerializeEdges();
   void SerializeImpl();
-  void SerializeNode(HeapEntry* entry, int edges_index);
-  void SerializeNodes(const List<HeapEntry>& nodes);
+  void SerializeNode(HeapEntry* entry);
+  void SerializeNodes();
   void SerializeSnapshot();
   void SerializeString(const unsigned char* s);
   void SerializeStrings();
   void SortHashMap(HashMap* map, List<HashMap::Entry*>* sorted_entries);
 
   static const int kEdgeFieldsCount;
   static const int kNodeFieldsCount;
 
   HeapSnapshot* snapshot_;
   HashMap strings_;
   int next_node_id_;
   int next_string_id_;
   OutputStreamWriter* writer_;
 
   friend class HeapSnapshotJSONSerializerEnumerator;
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_