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

tests/html/datalistelement_test.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.
 
-#library('datalistelement_dataview_test');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library datalistelement_dataview_test;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 main() {
   useHtmlConfiguration();
 
   var isDataListElement =
       predicate((x) => x is DataListElement, 'is a DataListElement');
 
   var div;
 
   setUp(() {
@@ skipping 31 matching lines @@
       var options = document.query('#browsers')
           .queryAll('option');  // Uses DataListElement.
       expect(options.length, 5);
   });
 
   test('create', () {
       var list = new DataListElement();
       expect(list, isDataListElement);
     });
 }