Optimize JSON stringify by allowing QuoteJSONString to prefix with a comma.

src/runtime.h

 // Copyright 2010 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 88 matching lines @@
   F(StringFromCharCodeArray, 1, 1) \
   F(StringParseInt, 2, 1) \
   F(StringParseFloat, 1, 1) \
   F(StringToLowerCase, 1, 1) \
   F(StringToUpperCase, 1, 1) \
   F(StringSplit, 3, 1) \
   F(CharFromCode, 1, 1) \
   F(URIEscape, 1, 1) \
   F(URIUnescape, 1, 1) \
   F(QuoteJSONString, 1, 1) \
+  F(QuoteJSONStringComma, 1, 1) \
   \
   F(NumberToString, 1, 1) \
   F(NumberToStringSkipCache, 1, 1) \
   F(NumberToInteger, 1, 1) \
   F(NumberToIntegerMapMinusZero, 1, 1) \
   F(NumberToJSUint32, 1, 1) \
   F(NumberToJSInt32, 1, 1) \
   F(NumberToSmi, 1, 1) \
   F(AllocateHeapNumber, 0, 1) \
   \
@@ skipping 430 matching lines @@
                                                 int position);
 
   // Helper functions used stubs.
   static void PerformGC(Object* result);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_