Update Button to be made of Material

sky/examples/widgets-fn/widgets_app.dart

Index: sky/examples/widgets-fn/widgets_app.dart
diff --git a/sky/examples/input/input_app.dart b/sky/examples/widgets-fn/widgets_app.dart
similarity index 61%
copy from sky/examples/input/input_app.dart
copy to sky/examples/widgets-fn/widgets_app.dart
index 68256cfc354b5354bbb45c457acda0403f96a97b..eaaa0a58eda4db3a94d9578cc66a5759aa98ed93 100644
--- a/sky/examples/input/input_app.dart
+++ b/sky/examples/widgets-fn/widgets_app.dart
@@ -3,10 +3,10 @@
 // found in the LICENSE file.
 
 import '../../framework/fn.dart';
-import '../../framework/components/input.dart';
+import '../../framework/components/button.dart';
 
-class InputApp extends App {
+class WidgetsApp extends App {
   Node build() {
-    return new Input();
+    return new Button(content: new Text('Go'), level: 1);
   }
 }