[abortsignal.html]
  [already-aborted AbortSignal then close() fires no events]
    expected: FAIL

  [abortController.abort() then close() fires no events]
    expected: FAIL

  [close() then abortController.abort() fires only one close event]
    expected: FAIL

  [already-aborted AbortSignal then Esc key fires no events]
    expected: FAIL

  [abortController.abort() then close via Esc key fires no events]
    expected: FAIL

  [Esc key then abortController.abort() fires only one close event]
    expected: FAIL

  [abortController.abort()ing a free CloseWatcher allows a new one to be created without a user activation]
    expected: FAIL

  [abortController.abort() inside oncancel]
    expected: FAIL

  [abortController.abort() inside onclose is benign]
    expected: FAIL