Summary:
Changelog: [iOS][Internal] - Add key modifier properties to the PointerEvent interface
This diff adds implementations of the `ctrlKey`, `shiftKey`, `altKey`, and `metaKey` properties on the PointerEvent interface for iOS.
Reviewed By: lunaleaps
Differential Revision: D37869377
fbshipit-source-id: b187bae93fbfc97b6ca1d8d9786ad85343484b3d