<!DOCTYPE html> <html> <head> <style type="text/css" media="screen"> iframe { border: 10px solid black; padding: 5px; margin: 20px; height: 150px; width: 300px; -webkit-box-shadow: 0 0 20px black; -webkit-transform: translateZ(0); } </style> <script type="text/javascript" charset="utf-8"> function doTest() { document.getElementById('iframe').className = 'dummy'; } window.addEventListener('load', doTest, false); </script> </head> <body> <iframe id="iframe" src="resources/composited-subframe.html"></iframe> <p><a href="https://bugs.webkit.org/show_bug.cgi?id=42046">https://bugs.webkit.org/show_bug.cgi?id=42046</a><br> You should see a blue rectangle inside the iframe when the page loads.</p> </body> </html>