Notifications: can't open panel with n keyboard shortcut key after recent Masterbar refactor

[lancewillett]

URL:
https://wpcalypso.wordpress.com/

What I expected:
To click n key on keyboard and open Notifications panel.

What happened instead:
Nothing opened, and I see a JS error in Chrome console.

client/layout/masterbar/notifications.jsx:67 TypeError: Failed to execute 'contains' on 'Node': parameter 1 is not of type 'Node'

Browser OS version:
Mac-n-Chrome desktop

Possibly caused by #631 work.

[lancewillett]

Thanks for the fix, @ehg. Works splendidly now.