[Feature] toggle PiP instead of just enabling PiP

[erictsangx]

toggle PiP instead of just enabling PiP upgrade to Swift4 as well

    const video = getVideo();
    video.webkitSetPresentationMode(video.webkitPresentationMode === 'picture-in-picture' ? 'inline' : 'picture-in-picture');

[MrMegaWatt13]

Ok