Mozilla Connect

That's odd. I still have the button "View recent browsing across windows and devices" that displays "Firefox View" while using vertical tabs. 

The bookmarks toolbar button might work for you.

There's a small space to the right of the address bar (right of the Bookmark this page button, if you have that button).

There's a toolbar button "List all tabs" you can use. Get it from "Customize toolbar..." if you don't already see it on your toolbar.

Someone posted an "idea" for this! Add your Kudos.https://connect.mozilla.org/t5/ideas/vertical-tabs-and-sidebar-inception/idi-p/89738#feedback-success