anchor.diff:     * This method assumes that the current token matches `TokenType.OPEN_PAREN`.
      */
     FormalParameterList _parseFormalParameterListUnchecked(
  -      {bool inFunctionType = false}) {
  +      {bool inFunctionType: false}) {
       return _parseFormalParameterListAfterParen(getAndAdvance(),
           inFunctionType: inFunctionType);
     }
  
positive.code:    *     namedFormalParameters ::=
     *         '{' defaultNamedParameter (',' defaultNamedParameter)* '}'
     */
    FormalParameterList parseFormalParameterList({bool inFunctionType = false}) {
      if (_matches(TokenType.OPEN_PAREN)) {
        return _parseFormalParameterListUnchecked(inFunctionType: inFunctionType);
      }
  
negative.code:    *         normalFormalParameter (':' expression)?
     */
    FormalParameter parseFormalParameter(ParameterKind kind,
        {bool inFunctionType: false}) {
      NormalFormalParameter parameter =
          parseNormalFormalParameter(inFunctionType: inFunctionType);
      TokenType type = _currentToken.type;
  