bug#46299: 28.0.50; Value of tab-bar-show not respected in new frames.

[Juri Linkov]

>> What if the user wants to manually enable the tab bar on one frame only
>> without enabling tab-bar-mode?  Currently it's possible with
>>
>>    (add-hook 'after-make-frame-functions 'toggle-frame-tab-bar)
>
> As a rule, this should be done by setting the 'tab-bar-lines' parameter
> of that frame to non-zero, leaving it at zero for all other frames.
>
> 'toggle-frame-tab-bar' should stick to that rule.

'toggle-frame-tab-bar' already does exactly this - sets the
'tab-bar-lines' parameter to non-zero, and doesn't change it
on all other frames.

But currently 'tab-bar-show' overrides this user setting,
and affects all other frames.