title: Safari doesn't call iframe onload when src is not valid site
body: <p>For the following iframe, Safari never calls the onload function and doesn't display anything in the iframe. All other browsers I've tested do call onload and display a default error web page.</p>
  
  <pre><code>&lt;html&gt;
  &lt;body&gt;
  &lt;iframe src="http://www.asdkjhjhkjhkjhjhjhfhkjhsdflkjahdsjfhasf.com"
          onload="alert('iframe loaded');"&gt;
  &lt;/iframe&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Why is this happening? If there is no solution to this problem, then I need to find a way to detect if an iframe fails to load.</p>