var getEls = document.getElementById('iframeHack').getElementsByTagName("IFRAME");

for (var i = 0; i < getEls.length; i++)
{
    getEls.item(i).style.width = getEls.item(i).nextSibling.offsetWidth;
	getEls.item(i).style.height = getEls.item(i).nextSibling.offsetHeight;
}