Allow hidden properties and implement GetIdentityHash

src/factory.h

 // Copyright 2006-2008 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 281 matching lines @@
 
 #define ROOT_ACCESSOR(type, name) \
   static Handle<type> name() { return Handle<type>(&Heap::name##_); }
   ROOT_LIST(ROOT_ACCESSOR)
 #undef ROOT_ACCESSOR_ACCESSOR
 
 #define SYMBOL_ACCESSOR(name, str) \
   static Handle<String> name() { return Handle<String>(&Heap::name##_); }
   SYMBOL_LIST(SYMBOL_ACCESSOR)
 #undef SYMBOL_ACCESSOR
+  
+  static Handle<String> hidden_symbol() {
+    return Handle<String>(&Heap::hidden_symbol_);
+  }
 
   static Handle<SharedFunctionInfo> NewSharedFunctionInfo(Handle<String> name);
 
   static Handle<Dictionary> DictionaryAtNumberPut(Handle<Dictionary>,
                                                   uint32_t key,
                                                   Handle<Object> value);
 
   static Handle<DebugInfo> NewDebugInfo(Handle<SharedFunctionInfo> shared);
 
 
@@ skipping 36 matching lines @@
   // Update the map cache in the global context with (keys, map)
   static Handle<MapCache> AddToMapCache(Handle<Context> context,
                                         Handle<FixedArray> keys,
                                         Handle<Map> map);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_