bug#63345: 28.2; provided-mode-derived-p doesn't work when passed an alias in MODES

[Eli Zaretskii]

> From: Damien Cassou <damien@cassou.me>
> Date: Sun, 07 May 2023 11:49:37 +0200
> 
> The function `provided-mode-derived-p` (used by `derived-mode-p`) has
> the code below. The first 3 lines of the function takes care of
> converting the first argument MODE if it is an alias (as
> `javascript-mode` is an alias for `js-mode`). This works great when
> calling the function this way:
> 
>   (provided-mode-derived-p 'javascript-mode 'prog-mode)
>     ⇒ prog-mode
> 
> But if the second argument MODES contains an alias, the code has no
> conversion mechanism and the line below returns nil even though I
> expect it to return non-nil:
> 
>   (provided-mode-derived-p 'javacript-mode 'javascript-mode)
>     ⇒ nil
> 
> Is that a bug?

Adding Stefan.