Update unittest to new package layout.

samples/tests/samples/lib/observable/observable_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('observable_tests');
 
 #import('dart:html');
 #import('../../../../ui_lib/observable/observable.dart');
-#import('../../../../../pkg/unittest/unittest.dart');
-#import('../../../../../pkg/unittest/html_config.dart');
+#import('../../../../../pkg/unittest/lib/unittest.dart');
+#import('../../../../../pkg/unittest/lib/html_config.dart');
 
 #source('abstract_observable_tests.dart');
 #source('change_event_tests.dart');
 #source('event_batch_tests.dart');
 #source('observable_list_tests.dart');
 #source('observable_value_tests.dart');
 
 void main() {
   useHtmlConfiguration();
   group('AbstractObservable', testAbstractObservable);
@@ skipping 20 matching lines @@
   validateEvent(e, target, pName, index, ChangeEvent.INSERT, newVal, null);
 }
 
 void validateRemove(ChangeEvent e, target, pName, index, oldVal) {
   validateEvent(e, target, pName, index, ChangeEvent.REMOVE, null, oldVal);
 }
 
 void validateUpdate(ChangeEvent e, target, pName, index, newVal, oldVal) {
   validateEvent(e, target, pName, index, ChangeEvent.UPDATE, newVal, oldVal);
 }