bug#47234: 28.0.50; frame-inner-height fails without window system on tab-bar-height

[martin rudalics]

> Is the following close to TRT?
>
> +     (if (fboundp 'tab-bar-height)
> +         (tab-bar-height frame t)
> +       (frame-parameter frame 'tab-bar-lines))

I think that `tab-bar-height' should be bound and return a meaningful
value everywhere.  The frame parameters (in particular for the menu and
tool bar) are only a meaningless pain in this regard.

Many thanks for spotting and working on this, martin