Students do not receive notifications when their assignment submission is graded

This bug relates to a QA test...

This test requires an assignment with a student submission. The student should have popup notification and email checked for assignment submissions in their messaging settings.

1. Login as a teacher and access the assignment.
2. Follow the 'View x submitted assignments' link and click a Grade link.
3. Add a grade and comment.
4. Login as the student and check that they receive a popup notification that their assignment submission has been graded.
5. Check that the student also receives email notification.

Grade feedback was saved and was available via 'view my submission' but no pop up notification was viewed by the student and no email was sent to the student.