fixing a typo and some half finished comment

grade/export/xml/grade_export_xml.php

@@ -75,7 +75,7 @@ class grade_export_xml extends grade_export {
                 $grade->grade_item =& $grade_item;
                 $gradestr = $grade->finalgrade; // no formating for now
                 
-                // MDL-11
+                // MDL-11669, skip exported grades or bad grades (if setting says so)
                 if ($export_tracking) {
                     $status = $geub->track($grade);
                     if ($this->updatedgradesonly && ($status == 'nochange' || $status == 'unknown')) {

grade/export/xml/index.php

@@ -55,7 +55,7 @@ $mform = new grade_export_form(null, array('idnumberrequired'=>true, 'publishing
 
 // process post information
 if ($data = $mform->get_data()) {
-    $export = new grade_export_xml($course, groups_get_course_group($course), $data->updatedgradesonly, false, false, $data->updatedgradesonly);
+    $export = new grade_export_xml($course, groups_get_course_group($course), '', false, false, $data->updatedgradesonly);
     // print the grades on screen for feedbacks
     $export->process_form($data);
     $export->print_continue();