- return elem.nodeType === 9 && elem.documentElement.nodeName !== "HTML" ||
- !!elem.ownerDocument && elem.ownerDocument.documentElement.nodeName !== "HTML";
+ // documentElement is verified for cases where it doesn't yet exist
+ // (such as loading iframes in IE - #4833)
+ return ((elem.ownerDocument || elem).documentElement || 0).nodeName !== "HTML";