assert_equals(getComputedStyle(myCE).getPropertyValue('color'), 'rgb(0, 255, 0)');
        assert_true(myCE.elementInternals.states.delete('--green'));
        assert_false(myCE.elementInternals.states.has('--green'));
        assert_equals(getComputedStyle(myCE).getPropertyValue('color'), 'rgb(255, 0, 0)');
        assert_false(myCE.elementInternals.states.delete('--green'));
    }, "states added multiple times counts as one");

    test(function(t) {
        myCE.elementInternals.states.add('--green');
  