Add @Native(...) annotation for native class names.

tests/compiler/dart2js_native/field_type_test.dart

Index: tests/compiler/dart2js_native/field_type_test.dart
diff --git a/tests/compiler/dart2js_native/field_type_test.dart b/tests/compiler/dart2js_native/field_type_test.dart
index bd2b1c1272155396d35ddeaecf8039468d31f922..75297ad3602f94a627c21a150e9fbe7b2e921561 100644
--- a/tests/compiler/dart2js_native/field_type_test.dart
+++ b/tests/compiler/dart2js_native/field_type_test.dart
@@ -6,9 +6,11 @@
 // This regression test verifies that compiler accounts for hidden constructor
 // when analysing field values.
 
+import "dart:_js_helper";
 import "package:expect/expect.dart";
 
-class Node native "Node" {
+@Native("Node")
+class Node {
 
   final Node parentNode;