anchor.diff:    problem(TreeNode node, String details, {TreeNode context}) {
       node ??= (context ?? this.context);
       int offset = node?.fileOffset ?? -1;
  +    String file = node?.location?.file ?? fileUri;
  +    Uri uri = file == null ? null : Uri.parse(file);
       LocatedMessage message = templateInternalVerificationError
           .withArguments(details)
  -        .withLocation(fileUri == null ? null : Uri.parse(fileUri), offset);
  +        .withLocation(uri, offset);
       CompilerContext.current.report(message, Severity.error);
       errors.add(message);
     }
  
positive.code: 
  import '../type_inference/type_schema.dart' show TypeSchemaVisitor, UnknownType;
  
  import 'redirecting_factory_body.dart' show RedirectingFactoryBody;
  
  List<LocatedMessage> verifyProgram(Program program, {bool isOutline: false}) {
    FastaVerifyingVisitor verifier = new FastaVerifyingVisitor(isOutline);
  
negative.code:         Member,
          Procedure,
          Program,
          StaticInvocation,
          SuperMethodInvocation,
          SuperPropertyGet,
          SuperPropertySet,
  