Remove visit and override visitExpression instead to make sure we check that the code produced for …

pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library tree_ir_nodes;
 
 import '../constants/expressions.dart';
 import '../constants/values.dart' as values;
-import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
 import '../dart_types.dart' show DartType, GenericType;
 import '../elements/elements.dart';
 import '../universe/universe.dart';
 import '../universe/universe.dart' show Selector;
 import 'optimization/optimization.dart';
 
 // The Tree language is the target of translation out of the CPS-based IR.
 //
 // The translation from CPS to Dart consists of several stages.  Among the
 // stages are translation to direct style, translation out of SSA, eliminating
@@ skipping 900 matching lines @@
     visitStatement(node.next);
   }
 
   visitCreateBox(CreateBox node) {
   }
 
   visitCreateInstance(CreateInstance node) {
     node.arguments.forEach(visitExpression);
   }
 }