Update unittest to new package layout.

pkg/unittest/lib/html_layout_config.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.
 
 /**
  * A configuration for running layoutr tests with testrunner.
  * This configuration is similar to the interactive_html_config
  * as it runs each test in its own IFrame. However, where the former
  * recreated the IFrame for each test, here the IFrames are preserved.
  * Furthermore we post a message on completion.
@@ skipping 290 matching lines @@
  */
 void useHtmlLayoutConfiguration() {
   if (window.location.search == '') { // This is the parent.
     _prepareDom();
     configure(new ParentHtmlConfiguration());
   } else {
     configure(new ChildHtmlConfiguration());
   }
 }