Summary:
Compared to what was planned, I added the `overflow` value which seemed missing. I had to modify the implementation a bit for all values which are backed by a `YGValue`, but we should probably enable the pixel dimensions in Objective-C and Swift somehow later.
Closes https://github.com/facebook/yoga/pull/322
Reviewed By: dshahidehpour
Differential Revision: D4386906
Pulled By: emilsjolander
fbshipit-source-id: 05ac0e571ef3a8ff0be31469e449a7b23f102218
8d320ceac2