Merge rewritten BATTERY wrappers
    
    Because we mimic Firefox behaviour, a Chromium derived browser
    becomes more easily fingerprintable. This can be fixed by properly
    wrapping `BatteryManager.prototype` getters and setters.
    
    Note that Chromium was also fingerprintable before the application of
    this merge as we used to delete BatteryManager and
    navigator.getBattery() returned undefine instead of a Promise.