bug#31699: 26.1.50; find-face-definition defaults to non-face symbol

[Basil L. Contovounesios]

The following:

1. emacs -Q
2. M-: (insert "major-mode") RET
3. M-x find-face-definition RET RET

results in the following *Messages* line:

  find-function-search-for-symbol:
    Don’t know where ‘major-mode’ is defined

This is due to find-function-read using (variable-at-point t) instead of
(face-at-point t) to calculate the default completion candidate, even
when given an argument of 'defface.

Patch to follow.

Thanks,

-- 
Basil

In GNU Emacs 26.1.50 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll 
bars)
 of 2018-06-03 built on thunk
Repository revision: 16e8541b743a6beb1926fef53cf1bfaed9c346db
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description:     Debian GNU/Linux testing (buster)