Update unittest to new package layout.

tests/html/element_add_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('ElementAddTest');
-#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();
 
   void expectNoSuchMethod(void fn()) =>
     Expect.throws(fn, (e) => e is NoSuchMethodError);
 
   group('addHTML', () {
@@ skipping 174 matching lines @@
       var child = new DivElement();
       parent.elements.add(child);
 
       parent.insertAdjacentText('beforeend', 'test');
 
       expect(parent.nodes.length, 2);
       expect(parent.nodes[1] is Text);
     });
   });
 }