Looking at the existing keyboard logic and the output HTML of the dropdown, the keyboard shortcuts need a lot of love and will have to be done a different way now.
It is no longer div.notification-options, it is span.notification-options, but more importantly, there is no list of options in the HTML output anymore (until the dropdown is clicked upon).
So with that in mind, it will need to use a different process for invoking these commands. I’ll see if I can track it down later this afternoon.