[Effen] s/Node/UINode/, s/Element/WrapperNode/, s/EventTarget/EventListenerNode/

sky/framework/components/button_base.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 '../fn.dart';
 
 abstract class ButtonBase extends Component {
   bool highlight = false;
 
   ButtonBase({ Object key }) : super(key: key);
 
-  Node buildContent();
+  UINode buildContent();
 
-  Node build() {
-    return new EventTarget(
+  UINode build() {
+    return new EventListenerNode(
       buildContent(),
       onPointerDown: _handlePointerDown,
       onPointerUp: _handlePointerUp,
       onPointerCancel: _handlePointerCancel
     );
   }
 
   void _handlePointerDown(_) {
     setState(() {
       highlight = true;
     });
   }
   void _handlePointerUp(_) {
     setState(() {
       highlight = false;
     });
   }
   void _handlePointerCancel(_) {
     setState(() {
       highlight = false;
     });
   }
 }