* lisp/tab-bar.el: Simplify internal functions.

* lisp/tab-bar.el: Simplify internal functions.

* lisp/tab-bar.el (tab-bar-tabs-set): New function.
(tab-bar-tabs): Use tab-bar--current-tab-find and tab-bar-tabs-set.
(tab-bar--tab): Use tab-bar--current-tab-find.
(tab-bar--current-tab): Remove unused line (assq 'current-tab ...)
because there is no current-tab when it's called.  Remove unused arg 'frame'.
(tab-bar--current-tab-find): Simplify.
(tab-bar-move-tab-to, tab-bar-move-tab-to-frame)
(tab-bar-new-tab-to, tab-bar-close-tab)
(tab-bar-close-other-tabs, tab-bar-undo-close-tab)
(tab-switcher-delete-from-list): Use tab-bar-tabs-set
instead of set-frame-parameter.
(tab-bar-close-group-tabs): Simplify using tab-bar--current-tab-find
without arg.