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

tests/compiler/dart2js_native/native_method_rename1_frog_test.dart

 // Copyright (c) 2011, 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.
 
 // Test the feature where the native string declares the native method's name.
 
 import 'native_testing.dart';
 import 'dart:_js_helper' show Native, JSName;
 
 @Native("A")
 class A {
   @JSName('fooA')
   int foo() native;
 
   @JSName('barA')
   int bar() native;
 
   @JSName('bazA')
   int baz() native;
 }
 
 A makeA() native;
 
 class B {
   int bar([x]) => 800;
   int baz() => 900;
 }
 
-void setup() native """
-// This code is all inside 'setup' and so not accessible from the global scope.
-function A(){}
-A.prototype.fooA = function(){return 100;};
-A.prototype.barA = function(){return 200;};
-A.prototype.bazA = function(){return 300;};
+void setup() {
+  JS('', r"""
+(function(){
+  // This code is inside 'setup' and so not accessible from the global scope.
+  function A(){}
+  A.prototype.fooA = function(){return 100;};
+  A.prototype.barA = function(){return 200;};
+  A.prototype.bazA = function(){return 300;};
 
-makeA = function(){return new A};
+  makeA = function(){return new A()};
 
-self.nativeConstructor(A);
-""";
+  self.nativeConstructor(A);
+})()""");
+}
 
 testDynamic() {
   var a = confuse(makeA());
   var b = confuse(new B());
 
   Expect.equals(100, a.foo());
   Expect.equals(200, a.bar());
   Expect.equals(300, a.baz());
   Expect.equals(800, b.bar());
   Expect.equals(900, b.baz());
@@ skipping 20 matching lines @@
 expectNoSuchMethod(action, note) {
   bool caught = false;
   try {
     action();
   } catch (ex) {
     caught = true;
     Expect.isTrue(ex is NoSuchMethodError, note);
   }
   Expect.isTrue(caught, note);
 }