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
Summary: `sizeThatFits:` can be expensive, this optimizes our measuring function so that we do not call it if we know that we are going to use the exact height and width that were passed-in.
Reviewed By: rnystrom
Differential Revision: D4023715
fbshipit-source-id: dc02703b50bafd168ffab62ed98a7f6342100cc9
Summary: If views are hidden on screen, we don't want to bother including them in layout calculations.
Reviewed By: rnystrom
Differential Revision: D4022992
fbshipit-source-id: 2e93eb911f26223f305ef7ce788f86d050b83e4a
Summary: I'm going to make some changes, but first, I want to get testing setup.
Reviewed By: rnystrom
Differential Revision: D4022585
fbshipit-source-id: a48516faad0bcb1a9cf5610ab21da5ee099c6f16
Summary: Add flexbox support to UIViews via a category
Reviewed By: dshahidehpour
Differential Revision: D4002873
fbshipit-source-id: f89de3acdf8fd89c7801918dcad34ba9011dd025
