Rename UINode to Widget.

sky/sdk/lib/widgets/navigator.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'basic.dart';
 
-typedef UINode Builder(Navigator navigator);
+typedef Widget Builder(Navigator navigator);
 
 abstract class RouteBase {
   RouteBase({this.name});
   final String name;
-  UINode build(Navigator navigator);
+  Widget build(Navigator navigator);
 }
 
 class Route extends RouteBase {
   Route({String name, this.builder}) : super(name: name);
   final Builder builder;
-  UINode build(Navigator navigator) => builder(navigator);
+  Widget build(Navigator navigator) => builder(navigator);
 }
 
 class Navigator extends Component {
   Navigator({Object key, this.currentRoute, this.routes})
     : super(key: key, stateful: true);
 
   RouteBase currentRoute;
   List<RouteBase> routes;
  
   void syncFields(Navigator source) {
@@ skipping 13 matching lines @@
     }
     assert(false);  // route not found
   }
 
   void pushRoute(RouteBase route) {
     setState(() {
       currentRoute = route;
     });
   }
 
-  UINode build() {
+  Widget build() {
     Route route = currentRoute == null ? routes[0] : currentRoute;
     assert(route != null);
     return route.build(this);
   }
-}
+}