Re-worked the logic for handling isXML detection.

diff --git a/src/selector.js b/src/selector.js
index 9fffeab..3371119 100644 (file)
--- a/src/selector.js
+++ b/src/selector.js
@@ -809,8 +809,8 @@ var contains = document.compareDocumentPosition ?  function(a, b){
 };
 
 var isXML = function(elem){
-       return elem && elem.nodeType === 9 && elem.nodeName !== "HTML" ||
-               isXML( elem.ownerDocument );
+       return elem.nodeType === 9 && elem.documentElement.nodeName !== "HTML" ||
+               !!elem.ownerDocument && isXML( elem.ownerDocument );
 };
 
 var posProcess = function(selector, context){