anchor.diff:          token = next;
           break;
         }
  -      var type = FormalParameterKind.optionalNamed;
  -      token = parseFormalParameter(token, type, kind).next;
  +      token =
  +          parseFormalParameter(token, FormalParameterKind.optionalNamed, kind)
  +              .next;
         ++parameterCount;
       } while (optional(',', token));
       if (parameterCount == 0) {
  
positive.code:           // Supply a non-empty method name so that it does not accidently
            // match the default constructor.
            token = insertSyntheticIdentifier(
                token, context, '\$_synthetic_field_name_${token.offset}');
          }
        }
      } else if (token.type.isBuiltIn && !context.isBuiltInIdentifierAllowed) {
  
negative.code:   /// message based on the given [context]. Return the synthetic identifier that
    /// was inserted.
    Token insertSyntheticIdentifier(Token token, IdentifierContext context,
        [String stringValue]) {
      // TODO(brianwilkerson) Accept the last consumed token.
      stringValue ??= '';
      Message message = context.recoveryTemplate.withArguments(token);
      Token identifier = new SyntheticStringToken(
          TokenType.IDENTIFIER, stringValue, token.charOffset, 0);
  