anchor.diff:        this.leftDelimiter,
         this.rightDelimiter,
         this.rightParenthesis) {
  -    _parameters = new NodeList<FormalParameter>(this, parameters);
  +    _parameters = new NodeListImpl<FormalParameter>(this, parameters);
     }
   
     @override
  
positive.code:    */
    ShowCombinatorImpl(Token keyword, List<SimpleIdentifier> shownNames)
        : super(keyword) {
      _shownNames = new NodeList<SimpleIdentifier>(this, shownNames);
    }
  
    @override
  
negative.code:   ListLiteralImpl(Token constKeyword, TypeArgumentList typeArguments,
        this.leftBracket, List<Expression> elements, this.rightBracket)
        : super(constKeyword, typeArguments) {
      _elements = new NodeListImpl<Expression>(this, elements);
    }
  
    @override
  