Add cross-origin test with credentials.

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_config.dart';
 import 'dart:html';
 import 'dart:json';
 
@@ skipping 21 matching lines @@
 
   test('XHR.get Cross-domain', () {
     var url = "http://localhost:9876/tests/html/xhr_cross_origin_data.txt";
     new HttpRequest.get(url, expectAsync1((xhr) {
       var data = JSON.parse(xhr.response);
       expect(data, contains('feed'));
       expect(data['feed'], contains('entry'));
       expect(data, isMap);
     }));
   });
+
+  test('XHR.getWithCredentials Cross-domain', () {
+    var url = "http://localhost:9876/tests/html/xhr_cross_origin_data.txt";
+    new HttpRequest.getWithCredentials(url, expectAsync1((xhr) {
+      var data = JSON.parse(xhr.response);
+      expect(data, contains('feed'));
+      expect(data['feed'], contains('entry'));
+      expect(data, isMap);
+    }));
+  });
 }