Don't hardcode the list of events types in fn

sky/examples/fn/widgets/menuitem.dart

Index: sky/examples/fn/widgets/menuitem.dart
diff --git a/sky/examples/fn/widgets/menuitem.dart b/sky/examples/fn/widgets/menuitem.dart
index 22cd8f75aa060f396d5debd1fd602fa515958902..6a7407b1d5d7575d29b0aca1930fb6734cc1cc3b 100644
--- a/sky/examples/fn/widgets/menuitem.dart
+++ b/sky/examples/fn/widgets/menuitem.dart
@@ -33,18 +33,11 @@ class MenuItem extends ButtonBase {
   List<Node> children;
   String icon;
 
-  sky.EventListener onClick;
-
-  MenuItem({ Object key, this.icon, this.children, this.onClick }) : super(key: key) {
-  }
+  MenuItem({ Object key, this.icon, this.children }) : super(key: key);
 
   Node render() {
     return new Container(
       style: _highlight ? _highlightStyle : _style,
-      onClick: onClick,
-      onPointerDown: _handlePointerDown,
-      onPointerUp: _handlePointerUp,
-      onPointerCancel: _handlePointerCancel,
       children: [
         super.render(),
         new Icon(