Fixed a bug with the isXMLDoc test - also made sure that isXMLDoc was handling...

Fixed a bug with the isXMLDoc test - also made sure that isXMLDoc was handling the case where documentElement is undefined (which only occurs on HTML documents in IE).

src/core.js

@@ -316,7 +316,8 @@ jQuery.extend({
 	isXMLDoc: function( elem ) {
 		// documentElement is verified for cases where it doesn't yet exist
 		// (such as loading iframes in IE - #4833)
-		return ((elem ? elem.ownerDocument || elem : 0).documentElement || 0).nodeName !== "HTML";
+		var documentElement = (elem ? elem.ownerDocument || elem : 0).documentElement;
+		return documentElement ? documentElement.nodeName !== "HTML" : false;
 	},
 
 	// Evalulates a script in a global context

test/unit/core.js

@@ -281,7 +281,7 @@ test("isXMLDoc - HTML", function() {
 
 	try {
 		var body = jQuery(iframe).contents()[0];
-		ok( jQuery.isXMLDoc( body ), "Iframe body element" );
+		ok( !jQuery.isXMLDoc( body ), "Iframe body element" );
 	} catch(e){
 		ok( false, "Iframe body element exception" );
 	}