Update the Mac OS watcher in pkg/watcher.

pkg/watcher/test/no_subscription/mac_os_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 'package:scheduled_test/scheduled_test.dart';
 import 'package:watcher/src/directory_watcher/mac_os.dart';
 import 'package:watcher/watcher.dart';
 
 import 'shared.dart';
 import '../utils.dart';
 
-// This is currently failing due to issue 14793. The reason is fairly complex:
-//
-// 1. As part of the test, an "unwatched.txt" file is created while there are no
-//    active watchers on the containing directory.
-//
-// 2. A watcher is then added.
-//
-// 3. The watcher lists the contents of the directory and notices that
-//    "unwatched.txt" already exists.
-//
-// 4. Since FSEvents reports past changes (issue 14373), the IO event stream
-//    emits a CREATED event for "unwatched.txt".
-//
-// 5. Due to issue 14793, the watcher cannot trust that this is really a CREATED
-//    event and checks the status of "unwatched.txt" on the filesystem against
-//    its internal state.
-//
-// 6. "unwatched.txt" exists on the filesystem and the watcher knows about it
-//    internally as well. It assumes this means that the file was modified.
-//
-// 7. The watcher emits an unexpected MODIFIED event for "unwatched.txt",
-//    causing the test to fail.
-//
-// Once issue 14793 is fixed, this will no longer be the case and the test will
-// work again.
-
 main() {
   initConfig();
 
   watcherFactory = (dir) => new MacOSDirectoryWatcher(dir);
 
   setUp(createSandbox);
 
   sharedTests();
 }