Fix `fader-label` test

[Zoltan]

not ok 104 Chrome 80.0 - [6048 ms] - Unit | Component | fader-label: isShowingChanged observer
    ---
        actual: >
            true
        expected: >
            false
        stack: >
                at http://localhost:7357/assets/tests.js:735:16
                at invoke (http://localhost:7357/assets/vendor.js:67434:16)
                at Queue.flush (http://localhost:7357/assets/vendor.js:67323:13)
                at DeferredActionQueues.flush (http://localhost:7357/assets/vendor.js:67520:21)
                at Backburner._end (http://localhost:7357/assets/vendor.js:68054:34)
                at Backburner.end (http://localhost:7357/assets/vendor.js:67804:12)
        negative: >
            false
        browser log: |