Summary:
@public
`YGNode.getStyle()` returns a reference to the enclosed `YGStyle` member. Assigning to a local copies unnecessarily.
Having eliminated the copy, we can also safely remove calls to `YGNode.setStyle()`, eliminating another copy.
Reviewed By: astreet
Differential Revision: D9083336
fbshipit-source-id: df8b603b5cc0b974cf5dd434c71956be4548e583