enerror = t.unreached_func(
            "iframe fullscreenerror event"
        );
        const outerPromise = makeChangeListener(document);
        const innerPromise = makeChangeListener(iframeDoc);
        const exitPromise = iframeDoc.exitFullscreen();

        const winningEvent = await Promise.race([outerPromise, innerPromise]);
        assert_equals(winningEvent.target, iframe);

        await Promise.allSettled([outerPromise, innerPromise, exitPromise]);
        assert_equals(
            document.f