Intermittent pass in /workers/semantics/run-a-worker/003.html

[jdm]

{
    "status": "OK", 
    "group": "default", 
    "message": null, 
    "stack": null, 
    "subtest": null, 
    "test": "/workers/semantics/run-a-worker/003.html", 
    "line": 118269, 
    "action": "test_result", 
    "expected": "ERROR"
}