Roll Observatory packages and add a roll script

packages/quiver/lib/src/iterables/cycle.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 34 matching lines @@
   T get current => _iterator.current;
 
   bool moveNext() {
     if (!_iterator.moveNext()) {
       _iterator = _iterable.iterator;
       return _iterator.moveNext();
     }
     return true;
   }
 }