Move more builtin files to strict mode.

src/json.js

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+"use strict";
+
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Array = global.Array;
 // var $String = global.String;
 
 var $JSON = global.JSON;
 
 // -------------------------------------------------------------------
 
 function Revive(holder, name, reviver) {
@@ skipping 215 matching lines @@
 
 // -------------------------------------------------------------------
 // JSON Builtins
 
 function JSONSerializeAdapter(key, object) {
   var holder = {};
   holder[key] = object;
   // No need to pass the actual holder since there is no replacer function.
   return JSONSerialize(key, holder, UNDEFINED, new InternalArray(), "", "");
 }