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

tests/html/element_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('ElementTest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library ElementTest;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 expectLargeRect(ClientRect rect) {
   expect(rect.top, 0);
   expect(rect.left, 0);
   expect(rect.width, greaterThan(100));
   expect(rect.height, greaterThan(100));
   expect(rect.bottom, rect.top + rect.height);
   expect(rect.right, rect.left + rect.width);
 }
 
@@ skipping 733 matching lines @@
     });
 
     test('getRange', () {
       var range = makeElList().getRange(1, 2);
       expect(range, isElementList);
       expect(range[0], isImageElement);
       expect(range[1], isInputElement);
     });
   });
 }