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

tests/compiler/dart2js_native/native_no_such_method_exception_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 "native_testing.dart";
 
 @Native("A")
 class A {
   bar() => 42;
 }
 
 @Native("B")
 class B {
   foo() => 42;
 }
 
 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();
   var exception;
   try {
     a.foo();
   } on NoSuchMethodError catch (e) {
     exception = e;
   }
   Expect.isNotNull(exception);
 }