bug#24543: 25.1; describe-symbol doesn't show face with same name as a variable

[Eli Zaretskii]

> From: Alex <agrambot@gmail.com>
> Date: Fri, 16 Jun 2017 15:54:45 -0600
> 
> > emacs -Q
> > C-h o font-lock-comment-face RET
> >
> > Only the variable of this name is shown, not the face (which can be
> > viewed with describe-face, of course).
> >
> > It appears that when the face only shares a name with a function, then
> > both the function and face are shown. Only a variable shadows the face
> > in describe-symbol.
> 
> This is because describe-symbol isn't returning (buffer-string) like
> describe-{function, variable} are.
> 
> I've attached a patch fixing this problem.

Thanks.  This LGTM, but doesn't the fact that describe-face's return
value will change after this constitute an incompatible change?  And
if so, could it break some of the users of this function out there?