fix index calculation to skip templates

Sortable.js

@@ -949,8 +949,10 @@
 	 */
 	function _index(/**HTMLElement*/el) {
 		var index = 0;
-		while (el && (el = el.previousElementSibling) && (el.nodeName.toUpperCase() !== 'TEMPLATE')) {
-			index++;
+		while (el && (el = el.previousElementSibling)) {
+			if (el.nodeName.toUpperCase() !== 'TEMPLATE') {
+				index++;
+			}
 		}
 		return index;
 	}