dillon1000/react

Support tangentialPressure and twist fields of pointer events (#13374)

While working on https://github.com/facebook/flow/pull/6728 I noticed React's recently-added `SyntheticPointerEvent` was missing the [`tangentialPressure`](https://www.w3.org/TR/pointerevents/#dom-pointerevent-tangentialpressure) and [`twist`](https://www.w3.org/TR/pointerevents/#dom-pointerevent-twist) fields. I couldn't find any reason for their omission in https://github.com/facebook/react/pull/12507 (nor in the spec) so I assume they were meant to be included, like the rest of `PointerEvent`. This PR adds these two fields to `SyntheticPointerEvent`.