Intermittent failure in /html/semantics/interactive-elements/the-details-element/toggleEvent.html

[gterzian]

{"status": "FAIL", "group": "default", "message": "assert_true: expected true got false", "stack": "@http://web-platform.test:8000/html/semantics/interactive-elements/the-details-element/toggleEvent.html:144:5\nTest.prototype.step_timeout/<@http://web-platform.test:8000/resources/testharness.js:1596:20\nTest.prototype.step@http://web-platform.test:8000/resources/testharness.js:1538:20\nTest.prototype.step_func/<@http://web-platform.test:8000/resources/testharness.js:1562:20\n", "subtest": "Setting open=true to opened 'details' element should not fire a toggle event at the 'details' element", "test": "/html/semantics/interactive-elements/the-details-element/toggleEvent.html", "line": 16093, "action": "test_result", "expected": "PASS"}

For example in #21325

[jdm]

  ▶ Unexpected subtest result in /html/semantics/interactive-elements/the-details-element/toggleEvent.html:
  │ FAIL [expected PASS] Calling open twice on 'details' fires only one toggle event
  │   → assert_true: expected true got false
  │ 
  │ @http://web-platform.test:8000/html/semantics/interactive-elements/the-details-element/toggleEvent.html:115:5
  │ Test.prototype.step_timeout/<@http://web-platform.test:8000/resources/testharness.js:1611:20
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1553:20
  └ Test.prototype.step_func/<@http://web-platform.test:8000/resources/testharness.js:1577:20

  ▶ Unexpected subtest result in /html/semantics/interactive-elements/the-details-element/toggleEvent.html:
  │ FAIL [expected PASS] Setting open=true to opened 'details' element should not fire a toggle event at the 'details' element
  │   → assert_true: expected true got false
  │ 
  │ @http://web-platform.test:8000/html/semantics/interactive-elements/the-details-element/toggleEvent.html:144:5
  │ Test.prototype.step_timeout/<@http://web-platform.test:8000/resources/testharness.js:1611:20
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1553:20
  └ Test.prototype.step_func/<@http://web-platform.test:8000/resources/testharness.js:1577:20