Roll Observatory packages and add a roll script

packages/web_components/lib/src/init.dart

 // Copyright (c) 2015, 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 web_components.src.init;
 
 import 'dart:async';
 import 'package:initialize/initialize.dart' show InitializerFilter;
 import 'package:web_components/web_components.dart';
 import 'mirror_initializer.dart' as init;
 export 'mirror_initializer.dart' show deployMode;
@@ skipping 11 matching lines @@
     bool initAll: true}) {
   if (typeFilter != null || customFilter != null) {
     return init.run(typeFilter: typeFilter, customFilter: customFilter);
   } else {
     return init
         .run(typeFilter: [HtmlImport])
         .then((_) => init.run(typeFilter: [CustomElement, CustomElementProxy]))
         .then((_) => initAll ? init.run() : null);
   }
 }