Roll Observatory packages and add a roll script

packages/watcher/test/no_subscription/mac_os_test.dart

Index: packages/watcher/test/no_subscription/mac_os_test.dart
diff --git a/packages/watcher/test/no_subscription/mac_os_test.dart b/packages/watcher/test/no_subscription/mac_os_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..d5b1c8e3fe815126846b809197dcddca477130a5
--- /dev/null
+++ b/packages/watcher/test/no_subscription/mac_os_test.dart
@@ -0,0 +1,19 @@
+// 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.
+
+@TestOn('mac-os')
+
+import 'package:scheduled_test/scheduled_test.dart';
+import 'package:watcher/src/directory_watcher/mac_os.dart';
+
+import 'shared.dart';
+import '../utils.dart';
+
+void main() {
+  watcherFactory = (dir) => new MacOSDirectoryWatcher(dir);
+
+  setUp(createSandbox);
+
+  sharedTests();
+}