[Slotable-interface.html]
  type: testharness
  [assignedSlot attribute must be defined on Element and Text interfaces]
    expected: FAIL

  [assignedSlot must return null when the node does not have an assigned node]
    expected: FAIL

  [assignedSlot must return the assigned slot]
    expected: FAIL

  [assignedSlot must return null when the assigned slot element is inside a closed shadow tree]
    expected: FAIL