Roll back r198729; it seems to be causing two testsuite failures if llvm is built with asserts -

210: test_with_dsym_and_run_command (Test-rdar-10642615.Radar10642615DataFormatterTestCase)
     Test data formatter commands. ... Assertion failed: (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"), function cast, file llvm/include/llvm/Support/Casting.h, line 239.

     226: test_with_dsym_and_run_command (Test-rdar-13338477.Radar13338477DataFormatterTestCase)
         Test that LLDB handles the clang typeclass Paren correctly. ... Assertion failed: (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"), function cast, file llvm/include/llvm/Support/Casting.h, line 239.