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

pkg/unittest/test/mock_stepwise_negative_test.dart

Index: pkg/unittest/test/mock_stepwise_negative_test.dart
===================================================================
--- pkg/unittest/test/mock_stepwise_negative_test.dart	(revision 14213)
+++ pkg/unittest/test/mock_stepwise_negative_test.dart	(working copy)
@@ -2,8 +2,9 @@
 // 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('unittestTest');
-#import('../../../pkg/unittest/unittest.dart');
+library mock_stepwise_negative_test;
+import '../../../pkg/unittest/lib/unittest.dart';
+import '../../../pkg/unittest/lib/mock.dart';
 
 main() {
   test('Mocking: stepwiseValidate', () {