Roll Observatory packages and add a roll script

packages/polymer/lib/src/build/polymer_bootstrap.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 polymer.src.build.polymer_bootstrap;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:code_transformers/messages/build_logger.dart';
 import 'package:code_transformers/assets.dart';
@@ skipping 54 matching lines @@
             resolveFromId: entryScriptId).then((polymerBootstrap) {
           transform.addOutput(polymerBootstrap);
           transform
               .addOutput(new Asset.fromString(primaryId, document.outerHtml));
           resolver.release();
         });
       });
     });
   }
 }