json bug fix

frog/lib/json.js

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // JavaScript implementation of the native methods declared in json.dart.
 
 // TODO(jmesserly): this needs lots of cleanup.
 // Ideally JS objects could be treated as Dart Maps directly, and then we can
 // really use native JSON.parse and JSON.stringify.
 
 
 var $JSON = JSON; // Save the real JSON
 
 JSON = function() {};
 JSON.parse = function(str) {
   return $JSON.parse(str, function(k, v) { return $convertJsToDart(v); });
 }
 
 // Shallow-converts the parsed JavaScript value into a Dart object, and
 // returns the Dart object.
 // Any component values have already been converted.
 function $convertJsToDart(obj) {
   if (obj != null && typeof obj == 'object' && !(obj instanceof Array)) {
     return $fixupJsObjectToDartMap(obj);
   }
+  return obj;
 }
 
 // Converts the parsed JavaScript Object into a Dart Map.
 function $fixupJsObjectToDartMap(obj) {
   var map = new HashMapImplementation();
   var keys = Object.keys(obj);
   for (var i = 0; i < keys.length; i++) {
     map.$setindex(keys[i], obj[keys[i]]);
   }
   return map;
@@ skipping 40 matching lines @@
 // Converts only shallowly.
 function $convertDartMapToJsObject(map) {
   var obj = {};
   var propertyNames = map.getKeys();
   for (var i = 0, len = propertyNames.length; i < len; i++) {
     var propertyName = propertyNames[i];
     obj[propertyName] = map.$index(propertyName);
   }
   return obj;
 }