pkg/unittest: tweaks to mock, re-enabled most tests

pkg/unittest/lib/html_enhanced_config.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.
 
 /**
  * A simple unit test library for running tests in a browser.
  *
  * Provides enhanced HTML output with collapsible group headers
  * and other at-a-glance information about the test results.
  */
 library unittest.html_enhanced_config;
 
-import 'dart:async';
 import 'dart:collection' show LinkedHashMap;
 import 'dart:convert';
 import 'dart:html';
 import 'unittest.dart';
 
 class HtmlEnhancedConfiguration extends SimpleConfiguration {
   /** Whether this is run within dartium layout tests. */
   final bool _isLayoutTest;
   HtmlEnhancedConfiguration(this._isLayoutTest);
 
@@ skipping 387 matching lines @@
 
   ''';
 }
 
 void useHtmlEnhancedConfiguration([bool isLayoutTest = false]) {
   unittestConfiguration = isLayoutTest ? _singletonLayout : _singletonNotLayout;
 }
 
 final _singletonLayout = new HtmlEnhancedConfiguration(true);
 final _singletonNotLayout = new HtmlEnhancedConfiguration(false);