message: Don't serialize diagnostics for tests.
diff: @@ -231,8 +231,8 @@ void Reflect(TVisitor& visitor, IndexFile& value) {
  REFLECT_MEMBER(last_modification_time);
  REFLECT_MEMBER(import_file);
  REFLECT_MEMBER(args);
  - }
  REFLECT_MEMBER(diagnostics);
  + }
  REFLECT_MEMBER(dependencies);
  REFLECT_MEMBER(types);
  REFLECT_MEMBER(funcs);
  