Move ASLayout frame to a computed property

AsyncDisplayKit/Layout/ASLayout.h

@@ -68,6 +68,12 @@ extern BOOL CGPointIsNull(CGPoint point);
  */
 @property (nonatomic, readonly, getter=isFlattened) BOOL flattened;
 
+/**
+ * @abstract Returns a valid frame for the current layout computed with the size and position.
+ * @discussion Clamps the layout's origin or position to 0 if any of the calculated values are infinite.
+ */
+@property (nonatomic, readonly) CGRect frame;
+
 /**
  * Initializer.
  *
@@ -142,12 +148,6 @@ extern BOOL CGPointIsNull(CGPoint point);
  */
 - (ASLayout *)flattenedLayoutUsingPredicateBlock:(BOOL (^)(ASLayout *evaluatedLayout))predicateBlock;
 
-/**
- * @abstract Returns a valid frame for the current layout computed with the size and position.
- * @discussion Clamps the layout's origin or position to 0 if any of the calculated values are infinite.
- */
-- (CGRect)frame;
-
 @end
 
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/Layout/ASLayout.mm

@@ -24,6 +24,8 @@ extern BOOL CGPointIsNull(CGPoint point)
 
 @implementation ASLayout
 
+@dynamic frame;
+
 + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
                       constrainedSizeRange:(ASSizeRange)sizeRange
                                       size:(CGSize)size