anchor.diff:      ..add(ifKeyword)
       ..add(leftParenthesis)
       ..add(_condition)
  -    ..add(rightParenthesis)
  -    ..add(elseKeyword);
  +    ..add(rightParenthesis);
   
     Expression get condition => _condition;
   
  
positive.code: ///
  ///    ifStatement ::=
  ///        'if' '(' [Expression] ')' [Statement] ('else' [Statement])?
  class IfStatementImpl extends StatementImpl implements IfStatement {
    /// The token representing the 'if' keyword.
    @override
    Token ifKeyword;
  
    /// The left parenthesis.
    @override
    Token leftParenthesis;
  
    /// The condition used to determine which of the statements is executed next.
    ExpressionImpl _condition;
  
    /// The right parenthesis.
    @override
    Token rightParenthesis;
  
    /// The statement that is executed if the condition evaluates to `true`.
    StatementImpl _thenStatement;
  
    /// The token representing the 'else' keyword, or `null` if there is no else
    /// statement.
    @override
    Token elseKeyword;
  
    /// The statement that is executed if the condition evaluates to `false`, or
    /// `null` if there is no else statement.
  
negative.code: 
    @override
    Iterable<SyntacticEntity> get childEntities => new ChildEntities()
      ..addAll(super.childEntities)
      ..add(_thenStatement)
      ..add(elseKeyword)
      ..add(_elseStatement);
  
    @override
    Statement get elseStatement => _elseStatement;
  