title: CSS transition with visibility not working
body: <p>In the fiddle below, I've a transition on visibility and opacity separately. The latter works but the former doesn't. Moreover, in case of visibility, the transition time is interpreted as delay on hover out. Happens in both Chrome &amp; Firefox. Is this a bug?</p>
  
  <p><a href="http://jsfiddle.net/0r218mdo/3/" rel="noreferrer">http://jsfiddle.net/0r218mdo/3/</a></p>
  
  <p>Case 1:</p>
  
  <pre><code>#inner{
      visibility:hidden;
      transition:visibility 1000ms;
  }
  #outer:hover #inner{
      visibility:visible;
  }
  </code></pre>
  
  <p>Case 2:</p>
  
  <pre><code>#inner1{
      opacity:0;
      transition:opacity 1000ms;
  }
  #outer1:hover #inner1{
      opacity:1;
  }
  </code></pre>