Fix the most significant "phantom notification" badness
When you receieve a notification about an object and then someone hides that object from you (or deletes it), you get a phantom notification which is very difficult to clear.
For now, test that notifications are visible when you open the menu and clear any that are not.
This could be a little more elegant than it is, but the current behavior is very clearly broken. This unbreaks it, at least.
- As Alice, configured task stuff to notify me (instead of sending email).
- As Bailey, added Alice as a subscriber to a task, then commented on it.
- As Alice, loaded home and saw a notification count. Didn't click it yet.
- As Bailey, set the task to private.
- As Alice, clicked the notification bell menu icon.
- Before change: no unread notifications, bell menu is semi-stuck in a phantom state which you can't clear.
- After change: bad notifications automatically cleared.
Reviewed By: amckinley
Differential Revision: https://secure.phabricator.com/D19384