Clean up examples directory

sky/examples/widgets-fn/widgets_app.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 'package:sky/framework/fn.dart';
-import 'package:sky/framework/components/button.dart';
-import 'package:sky/framework/components/popup_menu.dart';
-
-class WidgetsApp extends App {
-  static final Style _menuStyle = new Style('''
-    position: absolute;
-    top: 200px;
-    left: 200px;''');
-
-  Node build() {
-    return new Container(
-      children: [
-        new Button(key: 'Go', content: new Text('Go'), level: 1),
-        new Button(key: 'Back', content: new Text('Back'), level: 3),
-        new Container(
-          style: _menuStyle,
-          children: [
-            new PopupMenu(
-              items: [
-                [new Text('People & options')],
-                [new Text('New group conversation')],
-                [new Text('Turn history off')],
-                [new Text('Archive')],
-                [new Text('Delete')],
-                [new Text('Un-merge SMS')],
-                [new Text('Help & feeback')],
-              ],
-              level: 4),
-            ]
-          )
-        ]
-      );
-  }
-}