Also ban +new on YGLayout

Summary: `-init` is marked unavailable, but `+new` does the same thing and is not.

Reviewed By: dshahidehpour

Differential Revision: D8957391

fbshipit-source-id: 42fcfe845db79726d8724efd9f6a4d37c19938ad

YogaKit/Source/YGLayout.h

@@ -33,6 +33,13 @@ typedef NS_OPTIONS(NSInteger, YGDimensionFlexibility) {
 - (instancetype)init
     __attribute__((unavailable("you are not meant to initialise YGLayout")));
 
+/**
+ Make default init unavailable, as it will not initialise YGNode which is
+ required for the setters and getters of YGLayout's properties to work properly.
+ */
++ (instancetype)new
+    __attribute__((unavailable("you are not meant to initialise YGLayout")));
+
 /**
   The property that decides if we should include this view when calculating
   layout. Defaults to YES.