bug#54246: 29.0.50; EWW not showing images in some websites

[payas]

Hi,

I just rebuilt Emacs master with nativecomp+pgtk+imagemagick and can confirm 
the issue is still present.

I tested with full Doom-emacs config, a minimal from-scratch config as well as 
’wmacs -Q’ and issue is present on all 3.

Testing older Emacs version will be bit challenging for now, but I will see 
what I can do over coming week.

Also about the images being WebP/AVIF, I see an explicit image tag with `jpeg' 
file as src, can eww not prioritise that?
I disctinctly remember Emacs/EWW was able to show this in the past, but I 
cannot recall what version and library support that was.

┌────
│ <picture>
│ <source 
srcset="https://cdn.christine.website/file/christine-static/stickers/mara/happy.avif";
 type="image/avif">
│ <source 
srcset="https://cdn.christine.website/file/christine-static/stickers/mara/happy.webp";
 type="image/webp">
│ <img 
src="https://cdn.christine.website/file/christine-static/stickers/mara/happy.png";
 alt="Mara is happy">
│ </picture>
└────

Eli Zaretskii <eliz@gnu.org> writes:

> We want to move from ImageMagick because it has stability and
> security issues.  ImageMagick build is still supported, though.
>
> Emacs 29 also support externally converted images; see
> image-use-external-converter and image-converter.el.

I have tried doing this as well, but hasn’t worked for me yet. ’convert’ is 
present in PATH and Emacs variable is set but doesn’t seem to be working yet.
I will debug more when possible.

> We could also support building with libwebp and dav1d; patches
> welcome.

I know as much C as my cat, but I can help with testing and debugging if anyone 
else with the knowhow is willing to put in the time and work.

Thanks,
Payas