Menu in StocksApp should animate out

sky/framework/components/popup_menu_item.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 'animated_component.dart';
 import '../animation/animated_value.dart';
 import '../fn.dart';
 import 'ink_well.dart';
 
-class PopupMenuItem extends AnimatedComponent {
+class PopupMenuItem extends Component {
   static final Style _style = new Style('''
     min-width: 112px;
     padding: 16px;''');
 
   List<Node> children;
-  double _opacity;
+  double opacity;
 
-  PopupMenuItem({ Object key, this.children, AnimatedValue opacity}) : super(key: key) {
-    animateField(opacity, #_opacity);
-  }
+  PopupMenuItem({ Object key, this.children, this.opacity}) : super(key: key);
 
   Node build() {
-    return new InkWell(
-      style: _style,
-      inlineStyle: _opacity == null ? null : 'opacity: ${_opacity}',
-      children: children
-    );
+    return new StyleNode(
+      new InkWell(
+        inlineStyle: opacity == null ? null : 'opacity: ${opacity}',
+        children: children
+      ),
+      _style);
   }
 }