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

  [Custom button with command='show-popover' only opens popover.]
    expected: FAIL

  [Custom button with command='hide-popover' only closes popover.]
    expected: FAIL

  [Custom button with command='show-modal' opens dialog.]
    expected: FAIL

  [Custom button with command='close' closes dialog.]
    expected: FAIL

  [Custom button with command='request-close' closes open dialog and does nothing when dialog is already closed.]
    expected: FAIL

  [Custom button with custom command fires command event.]
    expected: FAIL