[Sema] Remove some dead logic
[Sema] Remove some dead logic

This conversion should already be handled by
`buildSelfReference`.

roambotics/swift,apple/swift,benlangmuir/swift,benlangmuir/swift,glessard/swift,glessard/swift,benlangmuir/swift,apple/swift,benlangmuir/swift,roambotics/swift,glessard/swift,glessard/swift,roambotics/swift,apple/swift,apple/swift,glessard/swift,benlangmuir/swift,apple/swift,roambotics/swift,glessard/swift,apple/swift,roambotics/swift,roambotics/swift,benlangmuir/swift