[Unit Tests] Add Text Layout Performance Tests (#2161)

* Add single-threaded text node performance testing

* Relax test a bit

AsyncDisplayKit/Details/CGRect+ASConvenience.h

@@ -13,6 +13,7 @@
 
 #import "ASBaseDefines.h"
 #import "ASLayoutController.h"
+#include "tgmath.h"
 
 #ifndef CGFLOAT_EPSILON
   #if CGFLOAT_IS_DOUBLE
@@ -26,6 +27,11 @@ NS_ASSUME_NONNULL_BEGIN
 
 ASDISPLAYNODE_EXTERN_C_BEGIN
 
+ASDISPLAYNODE_INLINE BOOL CGSizeEqualToSizeWithIn(CGSize size1, CGSize size2, CGFloat delta)
+{
+  return fabs(size1.width - size2.width) < delta && fabs(size1.height - size2.height) < delta;
+};
+
 struct ASDirectionalScreenfulBuffer {
   CGFloat positiveDirection; // Positive relative to iOS Core Animation layer coordinate space.
   CGFloat negativeDirection;