Update unittest to new package layout.

pkg/unittest/lib/html_config.dart

 // Copyright (c) 2011, 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.
  */
 #library('unittest');
 
 #import('dart:html');
 #import('unittest.dart');
 
-#source('html_print.dart');
+#source('src/html_print.dart');
 
 class HtmlConfiguration extends Configuration {
   /** Whether this is run within dartium layout tests. */
   final bool _isLayoutTest;
   HtmlConfiguration(this._isLayoutTest);
 
   // TODO(rnystrom): Get rid of this if we get canonical closures for methods.
   EventListener _onErrorClosure;
 
   void onInit() {
@@ skipping 14 matching lines @@
     window.on.error.remove(_onErrorClosure);
     _showResultsInPage(passed, failed, errors, results, _isLayoutTest,
         uncaughtError);
     window.postMessage('unittest-suite-done', '*');
   }
 }
 
 void useHtmlConfiguration([bool isLayoutTest = false]) {
   configure(new HtmlConfiguration(isLayoutTest));
 }