I'm surprised that it is not in the RTM, but I also do not find a bug for this in bugzilla. Many iPad users (as myself) complains about missing the tabbar, on Android FF has it: https://support.cdn.mozilla.net/media/uploads/gallery/images/2015-01-22-15-57-57-6e3efd.png It is a must have for iPad.
Might change one day in the future, but likely not in this bug.
And in which then? This is a must have for a big screen.
I know the UX team is currently working on updated designs for iPad screens. I'm not sure if there is a bug filed for it. NI'ing our UX team.