Comment # 2 on bug 104683 from Dieter Nützel

Can you both try this site, too?

http://webglsamples.org/aquarium/aquarium.html

It worked some days/weeks before XMas on RX580 (radeonsi) under Konqueror
(5.0.97).
Since then I get WebGL unsupportet with Firefox (57.0.4).

'It does not appear your computer supports WebGL.
Click here for more information.

Status: WebGL creation failed: * Error during native OpenGL init. * Error
during native OpenGL init. * Error during native OpenGL init. * Error during
native OpenGL init. * Error during native OpenGL init. * Exhausted GL driver
caps. * Exhausted GL driver options.'

Some subpages (Google) demos works with Konqueror (5.0.97)
http://webglsamples.org/blob/blob.html
http://webglsamples.org/dynamic-cubemap/dynamic-cubemap.html
http://webglsamples.org

But nothing with Firefox.

If this is unrelated I'll open my own bug.