bug#37630: 27.0.50; image-mode-fit-frame doesn't

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  37630@debbugs.gnu.org
> Date: Tue, 08 Oct 2019 17:47:44 +0200
> 
> In my experiments, this wasn't what failed.  (window-inside-edges)
> claimed that there was one more line in the frame than there actually is
> (but only in --with-x-toolkit=no builds; it computes the correct height
> in Gtk builds).

Why are we calculating the size in lines instead of pixels?  Could
that be the source of the problem?