MDL-49674 comment: Use correct format when displaying the comment

The plugin callback executed above can eventually change the format. We
need to use that one to have the formatting of the first AJAX response
consistent with following displays.

comment/lib.php

@@ -706,7 +706,7 @@ public function add($content, $format = FORMAT_MOODLE) {
             $newcmt->fullname = fullname($USER);
             $url = new moodle_url('/user/view.php', array('id' => $USER->id, 'course' => $this->courseid));
             $newcmt->profileurl = $url->out();
-            $newcmt->content = format_text($newcmt->content, $format, array('overflowdiv'=>true));
+            $newcmt->content = format_text($newcmt->content, $newcmt->format, array('overflowdiv'=>true));
             $newcmt->avatar = $OUTPUT->user_picture($USER, array('size'=>16));
 
             $commentlist = array($newcmt);