bug#41852: 27.0.50; text-scale commands don't scale header of tabulated-list-mode

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 31 Oct 2020 18:48:32 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 41852@debbugs.gnu.org, thomas.hisch@ims.co.at
> 
> > > I just did: fixed-pitch and variable-pitch.  Another example would be
> > > any defface that specifies :height as an absolute number of 1/10
> > > point.
> > 
> > I find that text inserted into a buffer using the fixed-pitch and
> > variable-pitch both scale.  But if I specify :height to be an absolute
> > number, the text does not scale.
> 
> Which means your fixed-pitch and variable-pitch faces don't specify
> the size of the font.  But otherwise what I said was correct, and
> should be taken into account.

And in any case, the scaling only affects the faces that are used to
display buffer text.  Other parts of the Emacs display, like display
margins and the mode line, aren't affected.  So the same face will
behave as scaled when it is on buffer text, and as unscaled elsewhere.
That's why we needed text-scale-remap-header-line-face in the first
place, right?  This is a subtlety that needs to be kept in mind, if
not made more widely known, when we are expecting that more and more
faces scale together with the default face.