Fix merge error: Call visitExpression instead of visit.

pkg/compiler/lib/src/js_backend/codegen/codegen.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 code_generator;
 
 import 'glue.dart';
 
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
@@ skipping 126 matching lines @@
   js.Expression visitConcatenateStrings(tree_ir.ConcatenateStrings node) {
     js.Expression addStrings(js.Expression left, js.Expression right) {
       return new js.Binary('+', left, right);
     }
 
     js.Expression toString(tree_ir.Expression input) {
       bool useDirectly = input is tree_ir.Constant &&
           (input.expression.value.isString ||
            input.expression.value.isInt ||
            input.expression.value.isBool);
-      js.Expression value = visit(input);
+      js.Expression value = visitExpression(input);
       if (useDirectly) {
         return value;
       } else {
         Element convertToString = glue.getStringConversion();
         registry.registerStaticUse(convertToString);
         js.Expression access = glue.staticFunctionAccess(convertToString);
         return (new js.Call(access, <js.Expression>[value]));
       }
     }
 
@@ skipping 377 matching lines @@
   void visitSetField(tree_ir.SetField node) {
     js.PropertyAccess field =
         new js.PropertyAccess.field(
             visitExpression(node.object),
             glue.instanceFieldPropertyName(node.field));
     js.Assignment asn = new js.Assignment(field, visitExpression(node.value));
     accumulator.add(new js.ExpressionStatement(asn));
     visitStatement(node.next);
   }
 }