Remove usage of dart:json.

tests/html/xhr_cross_origin_test.dart

 // Copyright (c) 2012, 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.
 
 library XHRCrossOriginTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
-import 'dart:json' as json;
+import "dart:convert";
 
 /**
  * Examine the value of "crossOriginPort" as passed in from the url from
  * [window.location] to determine what the cross-origin port is for
  * this test.
  */
  // TODO(efortuna): If we need to use this function frequently, make a
  // url_analyzer library that is part of test.dart that these tests can import.
 int get crossOriginPort {
   var searchUrl = window.location.search;
@@ skipping 15 matching lines @@
 
   group('functional', () {
 
     var port = crossOriginPort;
     var host = '${window.location.protocol}//${window.location.hostname}:$port';
 
     test('XHR.get Cross-domain', () {
       var gotError = false;
       var url = '$host/root_dart/tests/html/xhr_cross_origin_data.txt';
       return HttpRequest.request(url).then((xhr) {
-        var data = json.parse(xhr.response);
+        var data = JSON.decode(xhr.response);
         expect(data, contains('feed'));
         expect(data['feed'], contains('entry'));
         expect(data, isMap);
       }).catchError((error) {}, test: (error) {
         gotError = true;
         // Consume errors when not supporting cross origin.
         return !HttpRequest.supportsCrossOrigin;
       }).whenComplete(() {
         // Expect that we got an error when cross origin is not supported.
         expect(gotError, !HttpRequest.supportsCrossOrigin);
@@ skipping 10 matching lines @@
       var xhr = new HttpRequest();
       xhr.open('GET', url, async: true);
       var validate = expectAsync1((data) {
         expect(data, contains('feed'));
         expect(data['feed'], contains('entry'));
         expect(data, isMap);
       });
       xhr.onReadyStateChange.listen((e) {
         guardAsync(() {
           if (xhr.readyState == HttpRequest.DONE) {
-            validate(json.parse(xhr.response));
+            validate(JSON.decode(xhr.response));
           }
         });
       });
       xhr.send();
     });
 
     test('XHR.getWithCredentials Cross-domain', () {
       var url = '$host/root_dart/tests/html/xhr_cross_origin_data.txt';
       return HttpRequest.request(url, withCredentials: true).then((xhr) {
-        var data = json.parse(xhr.response);
+        var data = JSON.decode(xhr.response);
         expect(data, contains('feed'));
         expect(data['feed'], contains('entry'));
         expect(data, isMap);
       });
     });
   });
 }