Update unittest to new package layout.

tests/html/documentfragment_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('DocumentFragmentTest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
+#import('../../pkg/unittest/lib/unittest.dart');
+#import('../../pkg/unittest/lib/html_config.dart');
 #import('dart:html');
 #source('util.dart');
 
 main() {
   useHtmlConfiguration();
 
   Collection<String> _nodeStrings(Collection<Node> input) {
     var out = new List<String>();
     for (Node n in input) {
       if (n is Element) {
@@ skipping 327 matching lines @@
   //   // assertConstError(() => fragment.classes.add('foo'));
   // });
 
   test('query searches the fragment', () {
     var fragment = new DocumentFragment.html(
       "<div class='foo'><a>foo</a><b>bar</b></div>");
     Expect.equals("A", fragment.query(".foo a").tagName);
     Expect.listEquals(["A", "B"], _nodeStrings(fragment.queryAll(".foo *")));
   });
 }