Roll Observatory packages and add a roll script

charted/lib/core/utils/object_factory.dart

-//
-// Copyright 2014 Google Inc. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-//
-
-part of charted.core.utils;
-
-typedef T ObjectCreator<T>();
-
-/// Provides a registry and factory service.
-///
-/// Registration:
-/// ObjectFactory.register(“type”, () => { new TypeCreator(); });
-///
-/// Usage:
-/// instance = ObjectFactory.create('type');
-class ObjectFactory<T> {
-  Map<String, ObjectCreator<T>> _components = {};
-
-  /// Register a component [creator] for [name].
-  void register(String name, ObjectCreator<T> creator) {
-    _components[name] = creator;
-  }
-
-  /// Create an instance for [name].
-  T create(String name) {
-    if (!_components.containsKey(name)) {
-      throw new ArgumentError('Element $name not found in ComponentFactory');
-    }
-    var creator = _components[name],
-        instance = creator();
-    if (instance == null) {
-      throw new ArgumentError('Component $name initialization failed.');
-    }
-    return instance;
-  }
-}