Mark fn2's EventListenerNode work for PointerEvent

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';
+
+class ContainerApp extends App {
+  UINode build() {
+    return new EventListenerNode(
+      new Rectangle(0xFF00FFFF),
+      onPointerDown: _handlePointerDown);
+  }
+
+  void _handlePointerDown(sky.PointerEvent event) {
+    print("_handlePointerDown");
+  }
+}
+
+void main() {
+  new ContainerApp();
+}