Merge up to 8597 to experimental/gc from the bleeding edge.

test/mjsunit/regress/regress-crbug-84186.js

 // 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 21 matching lines @@
 var json = '{"key":"';
 var key = '';
 var expected = '';
 for(var i = 0; i < 60000; i++) {
   key = key + "TESTING" + i + "\\n";
   expected = expected + "TESTING" + i + "\n";
 }
 json = json + key  + '"}';
 var out = JSON.parse(json);
 assertEquals(expected, out.key);