Stub some constant to make the video viewable on Firefox

hololive-fc-firefox-stub.user.js

// ==UserScript==
// @name        Hololive FC Player Firefox Stub
// @namespace   Violentmonkey Scripts
// @match       https://hololive-fc.com/video/*
// @grant       none
// @version     1.0
// @author      Nightfeather
// @description 8/6/2023, 1:42:37 PM
// ==/UserScript==

/**
It looks like the video player it used is checking for PictureInPicture[^1] API, but firefox doesn't provided one atm,
makes it shows "This browser is not supported.".
But the player itself isn't configured to use this feature, so a fake class stub would work for me.

NOTE: THIS IS NOT A MEMBERSHIP BYPASS.

1: https://developer.mozilla.org/en-US/docs/Web/API/PictureInPictureWindow
*/

(() => {

  function PictureInPictureWindow() { return this; }
  function PictureInPictureEvent() { return this; }

  Object.defineProperty(window, 'PictureInPictureWindow', {
    value: PictureInPictureWindow,
    writable: false
  });

  Object.defineProperty(window, 'PictureInPictureEvent', {
    value: PictureInPictureEvent,
    writable: false
  })
})();