Intermittent WebGL failures

[gterzian]

{"status": "TIMEOUT", "group": "default", "message": null, "stack": null, "subtest": null, "test": "/_mozilla/webgl/conformance-1.0.3/conformance/renderbuffers/framebuffer-object-attachment.html", "line": 103719, "action": "test_result", "expected": "CRASH"}
{"status": "TIMEOUT", "group": "default", "message": null, "stack": null, "subtest": null, "test": "/_mozilla/webgl/conformance-2.0.0/conformance2/renderbuffers/framebuffer-object-attachment.html", "line": 106165, "action": "test_result", "expected": "CRASH"}
{"status": "TIMEOUT", "group": "default", "message": null, "stack": null, "subtest": null, "test": "/_mozilla/webgl/conformance-1.0.3/conformance/canvas/drawingbuffer-test.html", "line": 42833, "action": "test_result", "expected": "CRASH"}
{"status": "TIMEOUT", "group": "default", "message": null, "stack": null, "subtest": null, "test": "/_mozilla/webgl/conformance-1.0.3/conformance/canvas/drawingbuffer-static-canvas-test.html", "line": 50657, "action": "test_result", "expected": "CRASH"}

For example in #21325

The issue has been previously addressed in #21313

[nox]

Cc @jdm

[gterzian]

closing because aren't intermittent...