bug 356183 - Prevents CalDAV provider from throwing on VTODO retrieval. Patch by Bruno Browning <browning@uwalumni.com> r=lilmatt,jminta

calendar/providers/caldav/calDavCalendar.js

@@ -718,11 +718,11 @@ calDavCalendar.prototype = {
                         items = [ item ];
                     }
                     rv = Components.results.NS_OK;
-                } else if (item.QueryInterface(Ci.calIEvent)) {
+                } else if (item.instanceof Ci.calIEvent) {
                     iid = Ci.calIEvent;
                     rv = Components.results.NS_OK;
                     items = [ item ];
-                } else if (item.QueryInterface(Ci.calITodo)) {
+                } else if (item.instanceof Ci.calITodo) {
                     iid = Ci.calITodo;
                     rv = Components.results.NS_OK;
                     items = [ item ];