tests/html: removed usage of deprecated unittest features

tests/html/form_data_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 FormDataTest;
 
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
-void fail(message) {
-  guardAsync(() {
-    expect(false, isTrue, reason: message);
-  });
-}
-
 void main() {
   // TODO(efortuna): This is a bad test. Revisit when we have tests that can run
   // both a server and fire up a browser.
   useHtmlIndividualConfiguration();
 
   group('supported', () {
     test('supported', () {
       expect(FormData.supported, isTrue);
     });
   });
@@ skipping 45 matching lines @@
         var blob = new Blob(
             [blobString],
             'text/plain');
         form.appendBlob('theBlob', blob, 'theBlob.txt');
 
         var xhr = new HttpRequest();
         xhr.open('POST',
             '${window.location.protocol}//${window.location.host}/echo');
 
         xhr.onLoad.listen(expectAsync((e) {
-          expect(xhr.responseText.contains(blobString), true);
+          expect(xhr.responseText, contains(blobString));
         }));
         xhr.onError.listen((e) {
           fail('$e');
         });
         xhr.send(form);
       });
     }
   });
 }