<html class="reftest-wait"> <head> <script> function boom() { document.body.offsetHeight; var fourdiv = document.getElementById("four"); var parent = fourdiv.parentNode; var newdiv = document.createElement("div"); newdiv.appendChild(document.createTextNode("3")); parent.insertBefore(newdiv, fourdiv); document.body.offsetHeight; document.documentElement.className = ""; } </script> </head> <body onload="boom();"> <div>1</div> <div>2</div> <div id="four">4</div> <div>5</div> </body> </html>