title: html5 canvas with absolute position doesn't work
body: <p>Canvas with absolute position doesn't work as you can see here:
  <a href="http://jsfiddle.net/733zs/1/" rel="noreferrer">http://jsfiddle.net/733zs/1/</a> (Tested in Firefox and Chrome) The Rectangle should have a size of 500x500 pixel.</p>
  
  <p>Is there a way to make it work, without setting width and height manually? Or do I have made any mistakes?</p>