R1:e50b26941643

Notifications - fix race condition around "Mark All Read".

Summary:
pre-patch "Mark All Read" marks *all* unread notifications as read. This is a race condition in that the user is looking at some set of notiifcations and that set may update such that the newest notifications aren't shown. An example might be if sitting on the notifications page or having the menu open while a new notification comes in... Note re-opening the menu would show the latest notifications.

This patch makes it so "Mark All Read"…