bug#55696: 28.1; eshell fails to respect text-scale-increase

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 55696@debbugs.gnu.org, jeff.kowalski@gmail.com
> From: Jim Porter <jporterbugs@gmail.com>
> Date: Sun, 5 Jun 2022 11:12:50 -0700
> 
> > I think we should optimize the frequent case where
> > Vface_remapping_alist is nil, in which case BODY_IN_REMAPPED_CHARS is
> > the same as BODY_IN_CANONICAL_CHARS.  lookup_named_face is not a
> > trivial function, so it is best to avoid calling it whenever possible.
> 
> Good point. How does the updated implementation look?

Looks okay, except for one thing:

> +  if (pixelwise == BODY_IN_REMAPPED_CHARS)
> +    {
> +      if (Vface_remapping_alist)

This should be

         if (!NILP (Vface_remapping_alist))

because the implementation of nil is not necessarily an integer zero.
You will get compilation errors if you configure with the
"--enable-check-lisp-object-type" option.

I will do a more thorough review tomorrow.