message: Fixed a crash when dealing with an empty method name in the ObjC runtime.
  I've filed a bug covering better unit testing of our runtime metadata reader, which will allow this to be testable..
  <rdar://problem/31793264>
diff: @@ -355,9 +355,14 @@ public:
  }
  }
  + clang::IdentifierInfo **identifier_infos = selector_components.data();
  + if (!identifier_infos) {
  + return NULL;
  + }
  +
  clang::Selector sel = ast_ctx.Selectors.getSelector(
  is_zero_argument ? 0 : selector_components.size(),
  - selector_components.data());
  + identifier_infos);
  clang::QualType ret_type =
  ClangUtil::GetQualType(type_realizer_sp->RealizeType(
  