Use bitfields for enum members of `YGStyle`
Use bitfields for enum members of `YGStyle`

Summary:
@public

Puts all enum fields of `YGStyle` into bitfields. This saves 36 bytes (> 3%) per node.

Reviewed By: SidharthGuglani

Differential Revision: D13439606

fbshipit-source-id: b60a5444762041bc6f8cc5e04757034cb6893b30

facebook/css-layout,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/css-layout,facebook/css-layout,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/css-layout