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

tests/html/cssstyledeclaration_test.dart

 // Copyright (c) 2011, 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('CSSStyleDeclarationTest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library CSSStyleDeclarationTest;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 main() {
   useHtmlConfiguration();
 
   createTestStyle() {
     return new CSSStyleDeclaration.css("""
       color: blue;
       width: 2px !important;
     """);
   };
@@ skipping 71 matching lines @@
     window.setTimeout(expectAsync0(() {
       element.style.textDecoration = 'underline';
       element.getComputedStyle('').then(expectAsync1(
         (CSSStyleDeclaration style) {
           expect(style.textDecoration, equals('underline'));
         }
       ));
     }), 10);
   });
 }