Bug 217005 – [WebGL2] Add extension availability tests

• Status: NEW
• Component: WebGL

[Kenneth Russell]

In order to ensure that WebKit advertises the expected WebGL 1.0 and 2.0 extensions - and doesn't silently regress - it's necessary to add some layout tests verifying this.

The difficulty is that the advertised extensions differ from GPU to GPU, not just from platform to platform. TestExpectations can't currently suppress failures based on the GPU type on the system.

In Slack discussions, dino@ suggests to add an Internals method to either:

- Query the GPU type
- Query the expected extensions for the current platform
- Enable the WEBGL_debug_renderer_info extension and determine extension availability inside the test based on the result

or similar.

[Radar WebKit Bug Importer]

<rdar://problem/69903434>