R1:46d1a1d7c12c

When the user clicks the notification menu, hide it

Summary: Fixes T7905.

Test Plan: With Quicksand, clicked links and empty space in the notification menu.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7905

Differential Revision: https://secure.phabricator.com/D12541