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

tests/compiler/dart2js_native/subclassing_super_field_2_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 fields with same name as native fields.  We expect N.foo to have the
@@ skipping 18 matching lines @@
   Bfoo() => foo;
 
   toString() => '[N.foo = ${Nfoo()}, A.foo = ${Afoo()}, B.foo = ${Bfoo()}]';
 }
 
 B makeB() native;
 
 @Creates('=Object')
 getBPrototype() native;
 
-void setup() native r"""
-function B() { this.foo = 111; }  // N.foo
-makeB = function(){return new B;};
+void setup() {
+  JS('', r"""
+(function(){
+  function B() { this.foo = 111; }  // N.foo
+  makeB = function(){return new B()};
 
-getBPrototype = function(){return B.prototype;};
-""";
+  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(333, confuse(b).Bfoo());
   Expect.equals(222, confuse(b).Afoo());
   Expect.equals(111, confuse(b).Nfoo());
 
   Expect.equals(333, b.Bfoo());
   Expect.equals(222, b.Afoo());
   Expect.equals(111, b.Nfoo());
 }