Add hello_fn2.dart and make Text("Hello fn2") actually render something.

sky/examples/fn2/hello_fn2.dart

Index: sky/examples/fn2/hello_fn2.dart
diff --git a/sky/examples/hello_world/hello_world.dart b/sky/examples/fn2/hello_fn2.dart
similarity index 66%
copy from sky/examples/hello_world/hello_world.dart
copy to sky/examples/fn2/hello_fn2.dart
index e20978844d10f8c7caede32ccd867f74adece800..1aeda5d2ebc12d0dc5ab9d17586b64f0e99118af 100644
--- a/sky/examples/hello_world/hello_world.dart
+++ b/sky/examples/fn2/hello_fn2.dart
@@ -2,10 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:sky/framework/fn.dart';
+import 'package:sky/framework/fn2.dart';
 
 class HelloWorldApp extends App {
   UINode build() {
-    return new Text('Hello, world!');
+    return new Text('Hello, fn2!');
   }
 }
+
+void main() {
+  new HelloWorldApp();
+}