title: waitForKeyElements AJAX request not working
body: <p>I am using the <code>waitForKeyElements</code> function in a <code>tampermonkey</code> userscript to check for new tweets on twitter after an AJAX request occurs while scrolling the page down. <code>addCustomSearchResult()</code> is called after the initial page load and grabs those tweets.  </p>
  
  <p><code>addCustomSearchResult()</code> does not run when new tweets are loaded after the ajax call as I scroll down the page.  What am I doing wrong?</p>
  
  <pre><code>// @require     http://code.jquery.com/jquery-2.1.1.min.js
  // @require  https://gist.github.com/raw/2625891/waitForKeyElements.js
  // @grant    GM_addStyle
  
  waitForKeyElements("li.js-stream-item",addCustomSearchResult);
  function addCustomSearchResult (tweet) {
      console.log('found new tweet');
  }
  </code></pre>