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

tests/compiler/dart2js_native/native_method_rename2_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";
 
 @Native("A")
 class A {
   @JSName('fooA')
   int foo() native;
 }
 
 @Native("B")
 class B extends A {
   @JSName('fooB')
   int foo() native;
 }
 
 makeA() native;
 makeB() native;
 
-void setup() native """
-// This code is all inside 'setup' and so not accessible from the global scope.
-function inherits(child, parent) {
-  if (child.prototype.__proto__) {
-    child.prototype.__proto__ = parent.prototype;
-  } else {
-    function tmp() {};
-    tmp.prototype = parent.prototype;
-    child.prototype = new tmp();
-    child.prototype.constructor = child;
+void setup() {
+  JS('', r"""
+(function(){
+  // This code is inside 'setup' and so not accessible from the global scope.
+  function inherits(child, parent) {
+    if (child.prototype.__proto__) {
+      child.prototype.__proto__ = parent.prototype;
+    } else {
+      function tmp() {};
+      tmp.prototype = parent.prototype;
+      child.prototype = new tmp();
+      child.prototype.constructor = child;
+    }
   }
+  function A(){}
+  A.prototype.fooA = function(){return 100;};
+  function B(){}
+  inherits(B, A);
+  B.prototype.fooB = function(){return 200;};
+
+  makeA = function(){return new A()};
+  makeB = function(){return new B()};
+
+  self.nativeConstructor(A);
+  self.nativeConstructor(B);
+})()""");
 }
-function A(){}
-A.prototype.fooA = function(){return 100;};
-function B(){}
-inherits(B, A);
-B.prototype.fooB = function(){return 200;};
-
-makeA = function(){return new A};
-makeB = function(){return new B};
-
-self.nativeConstructor(A);
-self.nativeConstructor(B);
-""";
 
 testDynamic() {
   var things = [makeA(), makeB()];
   var a = things[0];
   var b = things[1];
 
   Expect.equals(100, a.foo());
   Expect.equals(200, b.foo());
 
   expectNoSuchMethod(() {
@@ skipping 30 matching lines @@
 expectNoSuchMethod(action, note) {
   bool caught = false;
   try {
     action();
   } catch (ex) {
     caught = true;
     Expect.isTrue(ex is NoSuchMethodError, note);
   }
   Expect.isTrue(caught, note);
 }