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

tests/compiler/dart2js_native/native_no_such_method_exception5_frog_test.dart

 // Copyright (c) 2012, 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 "dart:mirrors" show reflect;
 import "native_testing.dart";
 
 class GetName {
   foo(x, [y]) => "foo";
   baz(x, y, z) => "baz";
@@ skipping 12 matching lines @@
   baz() => 42;
 }
 
 class C {
   static create() => new C();
   noSuchMethod(x) => "${getName(x)}:${x.positionalArguments}";
 }
 
 makeA() native;
 
-setup() native """
+setup() {
+  JS('', r"""
+(function(){
   function A() {}
-  makeA = function() { return new A; }
+  makeA = function() { return new A(); };
   self.nativeConstructor(A);
-""";
+})()""");
+}
 
 main() {
   nativeTesting();
   setup();
   var a = makeA();
   a.bar();
   Expect.equals("native(foo:[1, 2])", a.foo(1, 2));
   Expect.equals("native(baz:[3, 4, 5])", a.baz(3, 4, 5));
   var c = C.create();
   Expect.equals("foo:[6]", c.foo(6));
 }