Update searchable_list test to run in package bots

lib/demo_app.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library searchable_list.demo_app;
 
 import 'package:polymer/polymer.dart';
 
 @CustomTag('demo-app')
 class DemoApp extends PolymerElement {
   @observable bool applyAuthorStyles = true;
   List<String> fruits = const [
       'Apple', 'Apricot', 'Avocado',
       'Banana', 'Blackberry', 'Blackcurrant', 'Blueberry',
       'Currant', 'Cherry', 'Clementine', 'Date', 'Durian', 'Fig',
       'Gooseberry', 'Grape', 'Grapefruit', 'Guava', 'Huckleberry',
       'Kiwi', 'Lemon', 'Lime', 'Lychee', 'Mandarin', 'Mango',
       'Cantaloupe', 'Honeydew melon', 'Nectarine', 'Orange',
       'Peach', 'Pear', 'Plum', 'Pineapple', 'Pomegranate',
       'Raspberry', 'Redcurrant', 'Star fruit', 'Strawberry',
       'Tangerine', 'Tomato', 'Watermelon'];
 
   DemoApp.created() : super.created();
 }