Roll Observatory packages and add a roll script

packages/watcher/lib/src/watch_event.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.
 
 library watcher.watch_event;
 
 /// An event describing a single change to the file system.
 class WatchEvent {
   /// The manner in which the file at [path] has changed.
   final ChangeType type;
@@ skipping 15 matching lines @@
   static const REMOVE = const ChangeType("remove");
 
   /// The contents of a file have changed.
   static const MODIFY = const ChangeType("modify");
 
   final String _name;
   const ChangeType(this._name);
 
   String toString() => _name;
 }