[proxies] Better print for proxies in d8

src/js/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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 170 matching lines @@
     } else {
       return SerializeObject(value, replacer, stack, indent, gap);
     }
   }
   // Undefined or a callable object.
   return UNDEFINED;
 }
 
 
 function JSONStringify(value, replacer, space) {
-  if (%_ArgumentsLength() == 1 && !%_IsJSProxy(value)) {
+  if (%_ArgumentsLength() == 1 && !IS_PROXY(value)) {
     return %BasicJSONStringify(value);
   }
   if (!IS_CALLABLE(replacer) && %is_arraylike(replacer)) {
     var property_list = new InternalArray();
     var seen_properties = new GlobalSet();
     var length = TO_LENGTH(replacer.length);
     for (var i = 0; i < length; i++) {
       var v = replacer[i];
       var item;
       if (IS_STRING(v)) {
@@ skipping 52 matching lines @@
 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(), "", "");
 }
 
 %InstallToContext(["json_serialize_adapter", JsonSerializeAdapter]);
 
 })