Clean up examples directory

sky/examples/stocks-fn/lib/stock_menu.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/components/popup_menu.dart';
-import 'package:sky/framework/fn.dart';
-import 'package:sky/framework/theme/view-configuration.dart';
-
-class StockMenu extends Component {
-  static final Style _style = new Style('''
-    position: absolute;
-    right: 8px;
-    top: ${8 + kStatusBarHeight}px;''');
-
-  PopupMenuController controller;
-
-  StockMenu({Object key, this.controller}) : super(key: key);
-
-  Node build() {
-    return new StyleNode(
-      new PopupMenu(
-        controller: controller,
-        items: [
-          [new Text('Add stock')],
-          [new Text('Remove stock')],
-          [new Text('Help & feeback')],
-        ],
-        level: 4),
-        _style
-    );
-  }
-}