title: `canplay` HTML5 Audio event not firing
body: <p>I'm trying to determine when an HTML5 audio element is ready to start playing so I can inform the user. I'm using the following code:</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      var audio = document.getElementById("audio")
  &lt;/script&gt;
  
  &lt;audio id="audio" hidden loop&gt;
  &lt;source src="/static/music/music.mp3" type="audio/mpeg"&gt;
  &lt;source src="/static/music/music.ogg" type="audio/ogg"&gt;
  &lt;source src="/static/music/music.wav" type="audio/wav"&gt;
  No support for HTML5 audio!
  &lt;/audio&gt;
  
  &lt;div id="playButton" onclick="audio.play();audio.addEventListener('canplay',function() {
      alert("ready!");
  });"&gt;PLAY&lt;/div&gt;
  </code></pre>
  
  <p>However, the alert never appears, even after pressing the playButton. Im using the lates Chrome (Chrome 40)</p>