anchor.diff:    }
   
     @override
  -  void visitFor(tree_ir.For node) {
  +  visitFor(tree_ir.For node) {
       js.Expression condition = visitExpression(node.condition);
       shortBreak.push(node.next);
       shortContinue.push(node);
  
positive.code:   js.Statement buildBodyStatement(tree_ir.Statement statement) {
      List<js.Statement> savedAccumulator = accumulator;
      accumulator = <js.Statement>[];
      visitStatement(statement);
      js.Statement result = _bodyAsStatement();
      accumulator = savedAccumulator;
      return result;
  
negative.code:   js.Fun buildFunction(tree_ir.FunctionDefinition function) {
      registerDefaultParameterValues(function.element);
      currentFunction = function.element;
      tree_ir.Statement statement = function.body;
      while (statement != null) {
        statement = visitStatement(statement);
      }
  
      List<js.Parameter> parameters = new List<js.Parameter>();
      Set<tree_ir.Variable> parameterSet = new Set<tree_ir.Variable>();
  