Add PointerEvent polyfill

[L1nkss]

Hello.
Is it possible to add polyfill for PointerEvent ?

[JakeChampion]

Yes, we could add https://github.com/wessberg/pointer-events but I can't see which browser versions it supports

[L1nkss]

It would be nice, thanks. We have already used that polyfill in our project and it's quite uncomfortable to load polyfills from two different sources.
I think it supports all browsers which don't support PointerEvent, but I'm not quite sure about that

[mhassan1]

That polyfill requires EventTarget and Constructable Events. We may need to address #252 and #1101, first.