Add a missing import to mac_os_watcher.

TBR

Review URL: https://codereview.chromium.org//68523020

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/watcher@30330 260f80e4-7a28-3924-810f-c04153c831b5

pkgs/watcher/test/directory_watcher/mac_os_test.dart

diff --git a/pkgs/watcher/test/directory_watcher/mac_os_test.dart b/pkgs/watcher/test/directory_watcher/mac_os_test.dart
index 8a30e27..7d31221 100644
--- a/pkgs/watcher/test/directory_watcher/mac_os_test.dart
+++ b/pkgs/watcher/test/directory_watcher/mac_os_test.dart
@@ -2,6 +2,8 @@
 // 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:scheduled_test/scheduled_test.dart';
 import 'package:watcher/src/directory_watcher/mac_os.dart';
 import 'package:watcher/watcher.dart';