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

pkg/intl/test/intl_message_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 intl_message_test;
 
 import '../lib/intl.dart';
-import '../../unittest/unittest.dart';
+import '../../../pkg/unittest/lib/unittest.dart';
 import '../lib/message_lookup_local.dart';
 
 /** Tests the MessageFormat library in dart. */
 
 class Person {
   String firstName, lastName;
   Person(this.firstName, this.lastName);
 }
 
 main() {
@@ skipping 64 matching lines @@
         desc: 'explains the locale');
     expect(Intl.withLocale('en-US', () => hello()), equals('locale=en-US'));
   });
 
   test('Test passing locale', () {
     hello(a_locale) => Intl.message('locale=${Intl.getCurrentLocale()}',
         desc: 'explains the locale', locale: a_locale);
     expect(hello('en-US'), equals('locale=en_US'));
   });
 }