starting to work on unit test config interface

pkg/unittest/lib/interactive_html_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.
 
 /**
  * This configuration can be used to rerun selected tests, as well
  * as see diagnostic output from tests. It runs each test in its own
  * IFrame, so the configuration consists of two parts - a 'parent'
  * config that manages all the tests, and a 'child' config for the
  * IFrame that runs the individual tests.
@@ skipping 46 matching lines @@
     ++idx2;
     var body = msg.substring(idx2);
 
     return new _Message(messageType, elapsed, body);
   }
 
   String toString() => text(messageType, elapsed, body);
 }
 
 
-class HtmlConfiguration extends Configuration {
+class HtmlConfiguration extends SimpleConfiguration {
   StreamSubscription _errorSubscription;
 
   void _installErrorHandler() {
     if (_errorSubscription == null) {
       _errorSubscription = window.onError.listen((e) {
         handleExternalError(e, '(DOM callback has errors)');
       });
     }
   }
 
@@ skipping 622 matching lines @@
 ul, menu, dir {
 display: block;
 list-style-type: disc;
 -webkit-margin-before: 1em;
 -webkit-margin-after: 1em;
 -webkit-margin-start: 0px;
 -webkit-margin-end: 0px;
 -webkit-padding-start: 40px;
 }
 """;