dart2js_native tests: Migrate 'native STRING' to JS-calls - part 2/2

tests/compiler/dart2js_native/native_class_inheritance4_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.
 
 import "native_testing.dart";
 
 // Additional Dart code may be 'placed on' hidden native classes.  With
 // inheritance, the superclass method must not be reached by a call on the
 // subclass.
 
@@ skipping 17 matching lines @@
   void set X(int x) {
     _field2 = x;
   }
 
   int method(int z) => _field2 + z;
 }
 
 A makeA() native;
 B makeB() native;
 
-void setup() native r"""
-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(){
+  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(){}
+  function B(){}
+  inherits(B, A);
+  makeA = function(){return new A()};
+  makeB = function(){return new B()};
+
+  self.nativeConstructor(A);
+  self.nativeConstructor(B);
+})()""");
 }
 
-function A(){}
-function B(){}
-inherits(B, A);
-makeA = function(){return new A;};
-makeB = function(){return new B;};
-
-self.nativeConstructor(A);
-self.nativeConstructor(B);
-""";
-
 testBasicA_dynamic() {
   setup(); // Fresh constructors.
 
   var a = [makeA()][0];
 
   a.X = 100;
   Expect.equals(100, a._field);
   Expect.equals(100, a.X);
   Expect.equals(150, a.method(50));
 }
@@ skipping 78 matching lines @@
 
 main() {
   nativeTesting();
   testBasicA_dynamic();
   testBasicA_typed();
   testBasicB_dynamic();
   testBasicB_typed();
   testAB_dynamic();
   testAB_typed();
 }