Update `react-art` to use new `prop-types` package

[flarnie]

Do you want to request a feature or report a bug?
Will stop react-art from throwing warnings when used with recent React. I haven't tested this manually, but it seems like it will throw because it's using the old style of getting PropTypes from React directly.

https://github.com/reactjs/react-art/blob/master/src/Wedge.art.js#L28

Also the package is not listing prop-types as a dependency -
https://github.com/reactjs/react-art/blob/master/package.json
and
https://github.com/facebook/react/blob/master/packages/react-art/package.json

What is the current behavior?
It probably throws a warning, or at least models out-of-date syntax which won't work once we deprecate React.PropTypes.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template: https://jsfiddle.net/ebsrpraL/).

TODO

What is the expected behavior?

Uses prop-types package, as shown in the docs.

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?

React 16.0 beta/RC

[gaearon]

Isn't this only relevant for old code in react-art repo? My understanding is that code is not used anywhere. Currently React repo is the source of truth, and we shouldn't have that problem in it.

[gaearon]

(Longer term we should move source of truth back into react-art but we can't until we expose the reconciler. There is an issue about this.)

[sophiebits]

Fixed by #10629.