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

utils/tests/pub/install/git/check_out_with_trailing_slash_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 pub_tests;
 
 import 'dart:io';
 
 import '../../test_pub.dart';
-import '../../../../../pkg/unittest/unittest.dart';
+import '../../../../../pkg/unittest/lib/unittest.dart';
 
 main() {
   group("(regression)", () {
     test('checks out a package from Git with a trailing slash', () {
       ensureGit();
 
       git('foo.git', [
         libDir('foo'),
         libPubspec('foo', '1.0.0')
       ]).scheduleCreate();
@@ skipping 13 matching lines @@
       dir(packagesPath, [
         dir('foo', [
           file('foo.dart', 'main() => "foo";')
         ])
       ]).scheduleValidate();
 
       run();
     });
   });
 }