title: document.dispatchEvent() not working in Firefox
body: <p>I'm having this problem where the <code>element.dispatchEvent(e);</code> isn't working properly in Firefox.</p>
  
  <p>The <a href="http://jsfiddle.net/gLcy9xqg/" rel="noreferrer">jsFiddle</a> example I'm having trouble with.</p>
  
  <p>The <code>element.dispatchEvent(e);</code> fires, and returns <code>true</code> but the desired event/effect doesn't happen, in the fiddle case, the opening of a <code>select</code> dropdown.</p>
  
  <p>It works fine with Chrome (Version 43.0.2357.134 m).<br>
  I'm using Firefox 39.0 to test this, don't know if this is the case with older versions or just the new one.</p>
  
  <p>Any pointers in the right direction would be appreciated. </p>