Bug 189179

We are seeing a crash on Intel GeminiLake platforms where the web process crashes with:

(WebKitWebProcess:5058): Gdk-ERROR **: The program 'WebKitWebProcess' received an X Window System error.
This probably reflects a bug in the program.
The error was 'GLXBadFBConfig'.
  (Details: serial 202 error_code 178 request_code 155 (GLX) minor_code 34)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the GDK_SYNCHRONIZE environment
   variable to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Tracing through, this happens because WebKit is calling glXCreateContextAttribsARB() with a NULL GLXFBConfig. This causes glvnd to raise an X error.

Why was GLContextGLX::createWindowContext unable to find a usable FBConfig? I don't fully understand the situation; I've provided some detail on it here:
https://lists.freedesktop.org/archives/xorg-devel/2018-August/057477.html

Regardless of that, it seems like webkit should probably do something better than it currently does (crash) when no config is found, e.g. fall back on non-composited gfx codepath?