fix up tests

test/list_path_observer_test.dart

 // Copyright (c) 2013, 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.
 
 import 'dart:async';
 import 'package:observe/observe.dart';
 import 'package:unittest/unittest.dart';
 import 'observe_test_utils.dart';
 
-main() => dirtyCheckZone().run(_runTests);
+import 'package:observe/mirrors_used.dart'; // make test smaller.
+import 'package:smoke/mirrors.dart';
+
+main() {
+  useMirrors();
+  dirtyCheckZone().run(_runTests);
+}
 
 _runTests() {
   var list;
   var obs;
   var o1, o2, o3;
   var sub;
   int changes;
 
   setUp(() {
     list = toObservable([
@@ skipping 47 matching lines @@
 class TestModel extends ChangeNotifier {
   var _a, _b;
   TestModel();
 
   get a => _a;
   void set a(newValue) { _a = notifyPropertyChange(#a, _a, newValue); }
 
   get b => _b;
   void set b(newValue) { _b = notifyPropertyChange(#b, _b, newValue); }
 }