Support "Date" as type

[MathiasWP]

Would be possible to add "Date" as a type?

import * as dom from 'dts-dom';

const dateType = dom.type.Date

I could add this, but i'm not sure how you want the API to look like. Should it be part of the dom.type.Date? Or should there exist a different API for setting the native JS objects as types?