title: dispatchEvent not triggering jQuery.on() event listener
body: <p>I have the following code that triggers a custom named event:</p>
  
  <pre><code>elem.addEventListener('click', function (event)
  {
      event.preventDefault();
  
      // Do some processing stuff
  
      var event = new Event('custom_event');
      this.dispatchEvent(event);
  });
  </code></pre>
  
  <p>If I try to catch the custom event with jQuery.on() it works, but only when I'm not using the descendant selector filter.</p>
  
  <p>So this works:</p>
  
  <pre><code>$('selector').on('custom_event', function () { // works });
  </code></pre>
  
  <p>But this doesn't:</p>
  
  <pre><code>$(document).on('custom_event', 'selector', function () { // doesn't work });
  </code></pre>
  
  <p>Can anyone shed some light on why that is? Here's a <a href="http://jsfiddle.net/zyu4ahnq/3/" rel="noreferrer">Fiddle</a> showing the problem.</p>