swift234

Use dynamic dispatch for [objc] properties and methods used in lvalues.

There are two major restrictions on this at the moment:
  1) It only applies to [objc] properties/subscripts (where we go
  through Objective-C dispatch). It still does static dispatch for
  non-[objc] properties/subscripts in classes.
  2) The Clang importer doesn't mark imported Objective-C properties
  and subscript operators as [objc], so this is useless in practice.



Swift SVN r8691