`expandable` widget does not work on local server

[kaycebasques]

Insert following code into a page:

<section class="expandable">
  <h3>Many options are available</h3>
  <button type="button" class="button-red button expand-control">Show Me</button>
  <ul>
    <li><a href="#">Option One</a></li>
    <li><a href="#">Option Two</a></li>
    <li><a href="#">Option Three</a></li>
  </ul>
</section>

Run the local server via start-appengine.sh.

The h3 and ul should be hidden until you press the button.

I can manage without it, but it makes me a little nervous that whenever I use this widget I won't be able to verify until it hits staging