bug#51883: 29.0.50; Command to get accidentally deleted frames back

[Juri Linkov]

> I haven't yet tested whether your implementation restores the tab-bar
> as well, or maybe it would require more handling.  I suspect that
> instead of framesets you might need to use window-state-get/window-state-put
> like it's used in 'clone-frame'.

Now I tested the recently added 'clone-frame' with the tab-bar,
and indeed cloning a frame with the tab-bar breaks the tabs
in the cloned frame, and breaks the tabs on the original frame.
The fix is pushed now in c25be3e7bb.