deleting dead code, making other code more obvious, and fixing a
bug.  This fixes these (bogus) warnings in release mode:

SemaExprObjC.cpp:383: warning: 'RHSProtoE' may be used uninitialized in this function
SemaExprObjC.cpp:383: warning: 'RHSProtoI' may be used uninitialized in this function

llvm-svn: 49984