Fix gesture events in fn2

sky/examples/fn2/container.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 'dart:sky' as sky;
 import 'package:sky/framework/fn2.dart';
 import 'package:sky/framework/rendering/box.dart';
 import '../lib/solid_color_box.dart';
 
 class Rectangle extends RenderNodeWrapper {
@@ skipping 20 matching lines @@
                   new Container(
                       decoration: new BoxDecoration(backgroundColor: const sky.Color(0xFFFFFF00)),
                       desiredSize: new sky.Size(double.INFINITY, 20.0)
                   ),
                   new Image(src: "https://www.dartlang.org/logos/dart-logo.png",
                             size: new sky.Size(300.0, 300.0),
                             key: 1
                   ),
               ])),
       ]),
-      onPointerDown: _handlePointerDown);
+      onPointerDown: _handlePointerDown,
+      onGestureTap: _handleGestureTap);
   }
 
   void _handlePointerDown(sky.PointerEvent event) {
     print("_handlePointerDown");
   }
+
+  void _handleGestureTap(sky.GestureEvent event) {
+    print("_handleGestureTap");
+  }
 }
 
 void main() {
   new ContainerApp();
 }