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

tests/html/unknownelement_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('UnknownElementTest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library UnknownElementTest;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 main() {
   useHtmlConfiguration();
 
   var isUnknownElement =
       predicate((x) => x is UnknownElement, 'is an UnknownELement');
 
   var foo = new Element.tag('foo');
   foo.id = 'foo';
   var bar = new Element.tag('bar');
@@ skipping 47 matching lines @@
 
       expect(foo.x, equals(42));
       expect(() { foo.x = 7; }, throwsNoSuchMethodError);
       expect(foo.id, equals('foo'));
       expect(() => bar.x, throwsNoSuchMethodError);
       bar.y = 11;
       expect(bar.y, equals(11));
       expect(foo.baz('hello'), equals('foo - hello'));
     });
 }