Roll Observatory packages and add a roll script

packages/quiver/lib/src/async/stream_router.dart

 // Copyright 2013 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 63 matching lines @@
 }
 
 typedef bool _Predicate(event);
 
 class _Route {
   final _Predicate predicate;
   final StreamController controller;
 
   _Route(this.predicate, this.controller);
 }