Add Test to make sure associated objects live/die with lifetime of UIView.

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

uikit/CSSLayout/UIView+CSSLayout.m

@@ -30,7 +30,6 @@ static void _updateFrameRecursive(UIView *view);
 
 - (void)dealloc
 {
-  [super dealloc];
   CSSNodeFree(_cnode);
 }
 @end