dart2js_native tests: Migrate 'native STRING' to JS-calls

tests/compiler/dart2js_native/oddly_named_fields_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';
 
 // JavaScript reserved words:
 //
 // break
 // case
@@ skipping 1363 matching lines @@
   if (object.yieldValue == null)
     throw 'incorrect initialization of "yieldValue"';
   object.yieldValue = true;
   if (!object.yieldValue) throw 'incorrect value in "yieldValue"';
   object.yieldValue = false;
   if (object.yieldValue) throw 'incorrect value in "yieldValue"';
 }
 
 NativeClassWithOddNames makeNativeClassWithOddNames() native;
 
-setup() native """
-function NativeClassWithOddNames() {}
-makeNativeClassWithOddNames = function() { return new NativeClassWithOddNames; }
-self.nativeConstructor(NativeClassWithOddNames);
-""";
+setup() {
+  JS('', r"""
+(function(){
+  function NativeClassWithOddNames() {}
+  makeNativeClassWithOddNames = function() {return new NativeClassWithOddNames()};
+  self.nativeConstructor(NativeClassWithOddNames);
+})()""");
+}
 
 main() {
   nativeTesting();
   setup();
   var object = makeNativeClassWithOddNames();
   object.testMyFields();
   testObjectStronglyTyped(object);
   testObjectWeaklyTyped([object]);
   testObjectWeaklyTyped(['fisk']);
   testObjectWeaklyTyped([new ClassWithOddNames()..testMyFields()]);
 }