Roll Observatory packages and add a roll script

packages/polymer/lib/src/build/polymer_smoke_generator.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.
 
 /// Transfomer that combines multiple Dart script tags into a single one.
 library polymer.src.build.polymer_smoke_generator;
 
 import 'dart:async';
 
 import 'package:html/dom.dart' show Document, Element, Text;
@@ skipping 716 matching lines @@
   for (var c in combinators) {
     if (c is ShowElementCombinator) {
       var show = c.shownNames.toSet();
       elements.retainWhere((e) => show.contains(e.displayName));
     } else if (c is HideElementCombinator) {
       var hide = c.hiddenNames.toSet();
       elements.removeWhere((e) => hide.contains(e.displayName));
     }
   }
 }