[behaves-like-button-with-popover.tentative.html]
  [Custom element with type=button and popovertargetaction='toggle' toggles popover.]
    expected: FAIL

  [Custom element with type=button and popovertargetaction='show' only opens popover.]
    expected: FAIL

  [Custom element with type=button and popovertargetaction='hide' only closes popover.]
    expected: FAIL

  [Custom element with type=button that is disabled does not support popovertarget.]
    expected: FAIL