bug#58799: Make winner key sequences repeatable in repeat-mode

[Stefan Kangas]

Robert Pluim <rpluim@gmail.com> writes:

>     (defvar-keymap winner-repeat-map
>       :doc "Keymap to repeat winner key sequences.  Used in `repeat-mode'."
>       <left> #'winner-undo
>       <right> #'winner-redo)
>
> (but you can stick them in a .el file)

Hmm, right.  I think that's a bug though, because when loading such a
.elc file I get:

keymap--check: [left] is not a valid key definition; see ‘key-valid-p’

So we should probably make sure that the `defvar-keymap' macro errors
out.