Restructure pkg/unittest and pkg/webdriver to follow the pub conventions.

tests/html/mutationobserver_test.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.
 
-#library('mutationobserver_test');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library mutationobserver_test;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 /**
  * Test suite for Mutation Observers. This is just a small set of sanity
  * checks, not a complete test suite.
  */
 main() {
   useHtmlConfiguration();
 
   group('childList', () {
 
@@ skipping 81 matching lines @@
         var div2 = new DivElement();
         var mutationObserver = new MutationObserver(
             mutationCallback(2, orderedEquals([div1, div2])));
         mutationObserver.observe(container, childList: true, subtree: true);
 
         container.nodes.add(div1);
         div1.nodes.add(div2);
       });
   });
 }