Allow front-end 'isa' access on object's of type 'id'.
Enhance test case to cover 'isa' access on interface types (clang produces an error, GCC produces a warning).

Still need back-end CodeGen for ObjCIsaExpr.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@76979 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed