Per @gibson042, don't need .documentElement since Sizzle handles.

dmethvin · dmethvin · commit 14f67a951894 · 2012-07-26T09:30:49.000-04:00
diff --git a/src/css.js b/src/css.js
@@ -45,7 +45,7 @@ function vendorPropName( style, name ) {
 
 function isHidden( elem, el ) {
 	elem = el || elem;
-	return jQuery.css( elem, "display" ) === "none" || !jQuery.contains( elem.ownerDocument.documentElement, elem );
+	return jQuery.css( elem, "display" ) === "none" || !jQuery.contains( elem.ownerDocument, elem );
 }
 
 function showHide( elements, show ) {

Original file line number	Diff line number	Diff line change
`@@ -45,7 +45,7 @@ function vendorPropName( style, name ) {`
`45`	`45`
`46`	`46`	`function isHidden( elem, el ) {`
`47`	`47`	`elem = el \|\| elem;`
`48`		`- return jQuery.css( elem, "display" ) === "none" \|\| !jQuery.contains( elem.ownerDocument.documentElement, elem );`
	`48`	`+ return jQuery.css( elem, "display" ) === "none" \|\| !jQuery.contains( elem.ownerDocument, elem );`
`49`	`49`	`}`
`50`	`50`
`51`	`51`	`function showHide( elements, show ) {`