add initWebComponents

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;
+
+/// Performs html import aware initialization by crawling all imported documents
+/// and initializing any script tags which appear in them.
+///
+/// By default, this will run all [HtmlImport] initializers, followed in a 2nd
+/// phase by all [CustomElement] and [CustomElementProxy] initializers. Then,
+/// unless [initAll] is [false], it will run all remaining initializers.
+///
+/// If a [typeFilter] or [customFilter] are supplied, only one phase is ran
+/// with the supplied filters.
+Future initWebComponents({List<Type> typeFilter, InitializerFilter customFilter,
+    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);
+  }
+}