Very intermittent crash running html/webappapis/dynamic-markup-insertion/opening-the-input-stream/tasks.window.js [as .tasks.window.html] with a window

[pshaughn]

This is in Mint 19.2 (in a VM without working GL support, but I doubt those details are relevant). Usually when I get an intermittent crash in a test that also times out I can associate the crash with the timeout, but in this case the timeout is #25092. It only happens occasionally and I don't get any stack trace info. Conceivably it's about frames being removed while their contentDocument is open, but that's a guess. It has never happened for me when headless.