Panic loading http://people.mozilla.org/~sicking/webgl/ray.html

[simartin]

This is to track the case reported by @dzbarsky in #8741, a different issue from the initial one

I've started to work on it and I believe the issue is we might not implement the "Automatic assignment" part of https://www.opengl.org/wiki/Vertex_Shader#Inputs

I'll continue to investigate, so feel free to assign the issue directly to me.

[simartin]

The issue is not linked to the missing "Automatic assignment" as I thought (I checked and Chrome does not do it...), but rather to the fact that we were blindly calling xyVertexAttribxy without checking the index we passed. This will generate a InvalidValue GL error if it's above MAX_VERTEX_ATTRIBS, in particular when it's -1, coming from a call to getAttribLocation for some unbound attribute.

[jdm]

Fixed by #10224.