test renaming overhaul: step 4 client tests

tests/html/xhr_tests.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.
 
 
 void testXHR() {
   print(window.location.href);
   asyncTest('XHR', 1, () {
     XMLHttpRequest xhr = new XMLHttpRequest();
     xhr.open("GET", "NonExistingFile", true);
     xhr.on.readyStateChange.add((event) {
         if (xhr.readyState == 4) {
           Expect.equals(0, xhr.status);
           Expect.stringEquals('', xhr.responseText);
           callbackDone();
         }
       });
     xhr.send();
   });
 }