Update unittest to new package layout.

samples/tests/samples/lib/util/util_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('util_tests');
 
 #import('dart:html');
-#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('../../../../ui_lib/util/utilslib.dart');
 
 main() {
   useHtmlConfiguration();
   test('insertAt', () {
     var a = [];
     CollectionUtils.insertAt(a, 0, 1);
     expect(a, orderedEquals([1]));
 
     CollectionUtils.insertAt(a, 0, 2);
@@ skipping 16 matching lines @@
     CollectionUtils.insertAt(a, 3, 5);
     expect(a, orderedEquals([1, 3, 2, 5, 4]));
   });
 
   test('defaultString', () {
     expect(StringUtils.defaultString(null), isEmpty);
     expect(StringUtils.defaultString(''), isEmpty);
     expect(StringUtils.defaultString('test'), equals('test'));
   });
 }