title: Web audio MediaElementSource node not being garbage collected
body: <p>In web audio, is there a trick to getting MediaElementSource nodes to be garbage collected? </p>
  
  <p>I've set up a page that adds two nodes: a MediaElementSource and an Oscillator. When I disconnect both of them, the Oscillator is garbage collected soon after, but the MediaElementSource stays permanently. (This is according to Firefox web audio dev tools which visualize the audio graph.)</p>
  
  <p>I'm experiencing this in both Chrome and Firefox on Mac (Yosemite).</p>
  
  <p>Why is the MediaElementSource node lingering permanently and is there any way to get rid of it without reloading the page or killing the audio context?</p>
  
  <pre><code>&lt;audio src="gam2.mp3" id="audio" controls&gt;&lt;/audio&gt;
  &lt;button onclick="disc()"&gt;disconnect&lt;/button&gt;
  
  &lt;script&gt;
  
      var actx = new AudioContext()
  
      var audio = document.getElementById("audio")
      var stream = actx.createMediaElementSource(audio)
      stream.connect(actx.destination)
  
      var sine = actx.createOscillator()
      sine.connect(actx.destination)
  
      function disc() {
          audio.remove()
          stream.disconnect()
          sine.disconnect()
      }
  
  &lt;/script&gt;
  </code></pre>