[pkg:mutation_observer] fix 12132, ie9 support

pkg/mutation_observer/test/mutation_observer_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 mutation_observer_test;
 
 import 'dart:html';
 import 'package:unittest/unittest.dart';
-import 'package:unittest/html_individual_config.dart';
+import 'package:unittest/html_config.dart';
 
 main() {
-  useHtmlIndividualConfiguration();
+  useHtmlConfiguration();
 
   // Load the MutationObserver polyfill.
   HttpRequest.getString('/root_dart/pkg/mutation_observer/lib/'
       'mutation_observer.min.js').then((code) {
 
     // Force MutationObserver polyfill to be used so we can test it, even in
     // browsers with native support.
     document.head.children.add(new ScriptElement()
         ..text = 'window.MutationObserver = void 0;'
                  'window.WebKitMutationObserver = void 0;'
@@ skipping 82 matching lines @@
     test('mutation event', () {
       var event = new MutationEvent('something', prevValue: 'prev',
           newValue: 'new', attrName: 'attr');
       expect(event is MutationEvent, isTrue);
       expect(event.prevValue, 'prev');
       expect(event.newValue, 'new');
       expect(event.attrName, 'attr');
     });
   });
 }