swift234

IRGen: super_method: Dynamically get superclass of static base class

After talking with @jckarter and @slavapestov we decided that getting
the superclass at runtime for super_method lookup was the right approach
if its based in the static base class and the lookup doesn't start with
  the instance pointer.

NFC for current IRGen - SILGen doesn't lead to here yet.

rdar://problem/22749732