Fix UAF, now leaks memory though :/ Please advise

Author: afflerbach

ext/dom/xpath_callbacks.c

@@ -440,6 +440,8 @@ static zend_result php_dom_xpath_callback_dispatch(php_dom_xpath_callbacks *xpat
 			obj = Z_DOMOBJ_P(&callback_retval);
 			nodep = dom_object_get_node(obj);
 			valuePush(ctxt, xmlXPathNewNodeSet(nodep));
+			/* keep document alive */
+			php_libxml_increment_doc_ref((php_libxml_node_object *) obj, nodep->doc);
 		} else if (Z_TYPE(callback_retval) == IS_FALSE || Z_TYPE(callback_retval) == IS_TRUE) {
 			valuePush(ctxt, xmlXPathNewBoolean(Z_TYPE(callback_retval) == IS_TRUE));
 		} else if (Z_TYPE(callback_retval) == IS_OBJECT) {