[Meta][WebGL] Fix WebGL conformance test failures.

[kalyankondapally]

As a first step, ensure we don't have any tests failing with Wayland as compared to X11 backend.

Run WebGL conformance tests in browser:
One can launch the page https://www.khronos.org/registry/webgl/sdk/tests/webgl-conformance-tests.html in browser
and run tests (all or a particular section they are interested in.)

Command to run WebGL conformance tests locally:
content/test/gpu/run_gpu_test --browser=exact --browser-executable=out/Debug/chrome --extra-browser-args=--no-sandbox webgl_conformance --webgl-conformance-version=1.0.3 -v

Dependency: #29.
Blocks: None.
SubTasks: #144 #159 #160 #161 #289 #291 #293 #298 #310 #325

[kalyankondapally]

We should be passing all the tests with latest Mesa.