title: HTML5 data-attributes in iframe element
body: <p>Can custom data-attributes set on an iframe be accessed by the iframe's content?</p>
  
  <p>Example:</p>
  
  <pre><code>&lt;iframe src="foo.html" data-something="123"&gt;&lt;/iframe&gt;
  </code></pre>
  
  <p>Is there a  way to access data-something's value form the iframe's document?</p>
  
  <p>Thanks.</p>