title: toDataURL not a function
body: <p>I am trying to generate a url for the canvas. Here are the steps I followed: </p>
  
  <pre><code>var can = document.getElementsByTagName("canvas");
  var src = can.toDataURL("image/png");
  </code></pre>
  
  <p>When I tried running the above code on firebug it throws an error : </p>
  
  <pre><code>TypeError: can.toDataURL is not a function
  </code></pre>
  
  <p>I am running firefox 8 on ubuntu.</p>