[d8] remove utility context.

src/d8.js

 // Copyright 2008 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.
 
+(function() {
 "use strict";
 
 // A more universal stringify that supports more types than JSON.
 // Used by the d8 shell to output results.
 var stringifyDepthLimit = 4;  // To avoid crashing on cyclic objects
 
 // Hacky solution to circumvent forcing --allow-natives-syntax for d8
 function isProxy(o) { return false };
 function JSProxyGetTarget(proxy) { };
 function JSProxyGetHandler(proxy) { };
@@ skipping 67 matching lines @@
 }
 
 function StringifyProxy(proxy, depth) {
   var proxy_type = typeof proxy;
   var info_object = {
     target: JSProxyGetTarget(proxy),
     handler: JSProxyGetHandler(proxy)
   }
   return '[' + proxy_type + ' Proxy ' + Stringify(info_object, depth-1) + ']';
 }
+
+return Stringify;
+})();