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

tests/html/element_constructor_1_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.
 
 // Put universally passing event constructors in this file.
 // Move constructors that fail on some configuration to their own
 // element_constructor_foo_test.dart file.
 
-#library('ElementConstructorTest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library ElementConstructorTest;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 main() {
   useHtmlConfiguration();
 
   var isAnchorElement = 
       predicate((x) => x is AnchorElement, 'is an AnchorElement');
   var isAreaElement = 
       predicate((x) => x is AreaElement, 'is an AreaElement');
   var isDivElement = predicate((x) => x is DivElement, 'is a DivElement');
   var isCanvasElement = 
@@ skipping 47 matching lines @@
   test('span', () {
       var e = new SpanElement();
       expect(e, isSpanElement);
     });
 
   test('select', () {
       var e = new SelectElement();
       expect(e, isSelectElement);
     });
 }