Call operator for objc.ObjCBlock<objc.CGSize Function(ffi.Pointer<ffi.Void>)>.
objc.ObjCBlock<objc.CGSize Function(ffi.Pointer<ffi.Void>)>
Available on ObjCBlock<CGSize Function(Pointer<Void>)>, provided by the ObjCBlock_CGSize_ffiVoid_CallExtension extension