Make integer indexed properties ("elements") work for proxies.

src/heap.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 1182 matching lines @@
     SYMBOL_LIST(SYMBOL_INDEX_DECLARATION)
 #undef SYMBOL_DECLARATION
 
     kSymbolTableRootIndex,
     kStrongRootListLength = kSymbolTableRootIndex,
     kRootListLength
   };
 
   MUST_USE_RESULT MaybeObject* NumberToString(
       Object* number, bool check_number_string_cache = true);
+  MUST_USE_RESULT MaybeObject* Uint32ToString(
+      uint32_t value, bool check_number_string_cache = true);
 
   Map* MapForExternalArrayType(ExternalArrayType array_type);
   RootListIndex RootIndexForExternalArrayType(
       ExternalArrayType array_type);
 
   void RecordStats(HeapStats* stats, bool take_snapshot = false);
 
   // Copy block of memory from src to dst. Size of block should be aligned
   // by pointer size.
   static inline void CopyBlock(Address dst, Address src, int byte_size);
@@ skipping 1102 matching lines @@
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 
 } }  // namespace v8::internal
 
 #undef HEAP
 
 #endif  // V8_HEAP_H_