title: Detect <iframe> height and width from inside the iframe
body: <p>I doubt this is actually possible but Im prepared to be corrected.</p>
  
  <p>What I need is to be able to detect the width and height of an iframe from within the iframe, so if the iframe <code>src</code> is <code>iframeContent.html</code> I need to be able to surface the values on this page.</p>
  
  <p>I have no control over the page that hosts the iframe only the contents of the iframe.</p>
  
  <p>Is this possible?</p>