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

tests/compiler/dart2js_native/subclassing_super_field_1_test.dart

 // Copyright (c) 2013, 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.
 
 import "native_testing.dart";
 import 'dart:_js_helper' show setNativeSubclassDispatchRecord;
 import 'dart:_interceptors'
     show findInterceptorForType, findConstructorForNativeSubclassType;
 
 // Test for shadowed fields in classes that extend native classes.
@@ skipping 14 matching lines @@
 
   Afoo() => super.foo;
   Bfoo() => foo;
 }
 
 B makeB() native;
 
 @Creates('=Object')
 getBPrototype() native;
 
-void setup() native r"""
+void setup() {
+  JS('', r"""
+(function(){
 function B() { }
-makeB = function(){return new B;};
+makeB = function(){return new B()};
 
 getBPrototype = function(){return B.prototype;};
-""";
+})()""");
+}
 
 main() {
   nativeTesting();
   setup();
 
   setNativeSubclassDispatchRecord(getBPrototype(), findInterceptorForType(B));
 
   B b = makeB();
 
   var constructor = findConstructorForNativeSubclassType(B, 'init');
   Expect.isNotNull(constructor);
   JS('', '#(#)', constructor, b);
 
   print(b);
 
   Expect.equals(222, confuse(b).Bfoo());
   Expect.equals(111, confuse(b).Afoo());
 
   Expect.equals(222, b.Bfoo());
   Expect.equals(111, b.Afoo());
 }