dart2js_native tests: Migrate 'native STRING' to JS-calls - part 2/2

tests/compiler/dart2js_native/subclassing_4_test.dart

Index: tests/compiler/dart2js_native/subclassing_4_test.dart
diff --git a/tests/compiler/dart2js_native/subclassing_4_test.dart b/tests/compiler/dart2js_native/subclassing_4_test.dart
index b1bf47092b028242e032ccced5787d59e40f6edc..07a2d4cb7bb48b140c6159e11b5d8e118fca9927 100644
--- a/tests/compiler/dart2js_native/subclassing_4_test.dart
+++ b/tests/compiler/dart2js_native/subclassing_4_test.dart
@@ -32,11 +32,14 @@ B makeB() native;
 @Creates('=Object')
 getBPrototype() native;
 
-void setup() native r"""
-function B() {}
-makeB = function(){return new B;};
-getBPrototype = function(){return B.prototype;};
-""";
+void setup() {
+  JS('', r"""
+(function(){
+  function B() {}
+  makeB = function(){return new B()};
+  getBPrototype = function(){return B.prototype;};
+})()""");
+}
 
 main() {
   nativeTesting();