Summary: Wrote some tests to make sure the associated objects we use for layout live and die with the objects. This was worthwhile because it made me realize UIView+CSSLayout wasn't enabled to ARC. As a result, my tests were failing because they weren't explicitly deallocing nodes.
Reviewed By: rnystrom
Differential Revision: D4023324
fbshipit-source-id: 5356cf4f0522582d75f83b5eb2193d9bc8d63aee
eedee80f25