Implementing custom element's attributeChanged callback in Dartium

tests/html/custom/entered_left_view_test.dart

 // Copyright (c) 2013, 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 entered_left_view_test;
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:js' as js;
 import 'package:unittest/html_individual_config.dart';
@@ skipping 109 matching lines @@
           reason: 'calling the constructor should invoke the created callback');
     });
 
     test('Entered document without a view', () {
       docB.body.append(a);
       expect(invocations, [],
           reason: 'entered callback should not be invoked when entering a '
           'document without a view');
     });
 
-    /*
     test('Attribute changed in document without a view', () {
       a.setAttribute('data-foo', 'bar');
       expect(invocations, ['attribute changed'],
           reason: 'changing an attribute should invoke the callback, even in a '
           'document without a view');
     });
-    */
+
     test('Entered document with a view', () {
       document.body.append(a);
       customElementsTakeRecords();
       expect(invocations, ['entered'],
           reason: 'entered callback should be invoked when entering a document '
           'with a view');
     });
 
     test('Left document with a view', () {
       a.remove();
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       Platform.upgradeCustomElements(div);
       invocations = [];
       document.body.append(div);
       customElementsTakeRecords();
       expect(invocations, ['entered'],
           reason: 'the entered callback should be invoked when inserted into a '
           'document with a view as part of a subtree');
     });
   });
 }