bug#67654: 29.1; Hiding menu bar makes new frames very small

[Roshan Shariff <roshan.shariff@gmail.com>]

I tried a git bisect only to find that commits as far back as ~2015
exhibit the bug; I wasn't able to compile older versions on my system
because of segfaults during compilation. So it seems plausible that
the GTK3 build of Emacs has always had this issue.

While coming up with a workaround (see below) I noticed something odd.
I added a hook to after-make-frame-functions that prints out the
frame-{char,native,text,outer}-{width,height} of the newly created
frame. I found that immediately after the frame is created, these
values are fine. But when printing them out after a brief sleep-for,
or using run-with-timer, the values actually match the size of the
tiny frame. So it seems that Emacs thinks the frame has the correct
size on creation, but learns of its actual size a little bit later.

The following workaround needs the run-with-timer (and the duration
needs to be long enough):

(add-hook 'after-make-frame-functions
   (defun +resize-after-make-frame (frame)
     ;; HACK Resize new frames shortly after creation.  Works around
     ;; https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67654
     (when-let ((width (alist-get 'width default-frame-alist))
                (height (alist-get 'height default-frame-alist)))
       (run-with-timer (/ 1.0 60) nil #'set-frame-size frame width height))))

I figure there's little chance of finding the root cause, but
hopefully the workaround will help people who come across this.