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

utils/tests/pub/install/git/stay_locked_if_compatible_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() {
   test("doesn't update a locked Git package with a new compatible "
       "constraint", () {
     ensureGit();
 
     git('foo.git', [
       libDir('foo', 'foo 1.0.0'),
       libPubspec("foo", "1.0.0")
     ]).scheduleCreate();
@@ skipping 21 matching lines @@
 
     dir(packagesPath, [
       dir('foo', [
         file('foo.dart', 'main() => "foo 1.0.0";')
       ])
     ]).scheduleValidate();
 
     run();
   });
 }