anchor.diff:  }
   
   mixin ForMixin on AstNodeImpl {
  -  Token? awaitKeyword;
  -
  -  late Token forKeyword;
  -
  -  late Token leftParenthesis;
  -
  -  late ForLoopPartsImpl _forLoopParts;
  -
  -  late Token rightParenthesis;
  +  Token? get awaitKeyword;
   
     @override
     Token get beginToken => awaitKeyword ?? forKeyword;
  
positive.code:       List<Configuration>? configurations,
        this.deferredKeyword,
        this.asKeyword,
        SimpleIdentifierImpl? prefix,
        List<Combinator>? combinators,
        Token semicolon)
        : super(comment, metadata, keyword, libraryUri, configurations,
              combinators, semicolon) {
      _prefix = _becomeParentOf(prefix);
    }
  
    @override
  
negative.code:   Token operator;
  
    /// The expression computing the operand for the operator.
    ExpressionImpl _operand;
  
    /// The element associated with the operator based on the static type of the
    /// operand, or `null` if the AST structure has not been resolved, if the
  