Intermittent failure in /webgl/conformance-1.0.3/conformance/canvas/buffer-offscreen-test.html

[jdm]

  ▶ Unexpected subtest result in /webgl/conformance-1.0.3/conformance/canvas/buffer-offscreen-test.html:
  │ FAIL [expected PASS] WebGL test #4: at (0, 10) expected: 0,0,255,255 was 255,0,0,255
  │   → assert_true: at (0, 10) expected: 0,0,255,255 was 255,0,0,255 expected true got false
  │ 
  │ reportTestResultsToHarness/<@http://web-platform.test:8000/webgl/conformance-1.0.3/resources/js-test-pre.js:88:9
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1406:20
  │ test@http://web-platform.test:8000/resources/testharness.js:497:9
  │ reportTestResultsToHarness@http://web-platform.test:8000/webgl/conformance-1.0.3/resources/js-test-pre.js:87:7
  │ testFailed@http://web-platform.test:8000/webgl/conformance-1.0.3/resources/js-test-pre.js:159:5
  │ checkCanvasRectColor@http://web-platform.test:8000/webgl/conformance-1.0.3/conformance/resources/webgl-test-utils.js:1047:9
  │ checkCanvasRect@http://web-platform.test:8000/webgl/conformance-1.0.3/conformance/resources/webgl-test-utils.js:1073:3
  │ @http://web-platform.test:8000/webgl/conformance-1.0.3/conformance/canvas/buffer-offscreen-test.html:84:5
  └ waitForComposite/countDown@http://web-platform.test:8000/webgl/conformance-1.0.3/conformance/resources/webgl-test-utils.js:2494:7