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

tests/compiler/dart2js_native/native_call_arity2_frog_test.dart

Index: tests/compiler/dart2js_native/native_call_arity2_frog_test.dart
diff --git a/tests/compiler/dart2js_native/native_call_arity2_frog_test.dart b/tests/compiler/dart2js_native/native_call_arity2_frog_test.dart
index 47821e585c1fd94a50e6cbccc738df40d9ab40f6..f1289ffce395f9e23d6ee7c5447f095074ddc1f9 100644
--- a/tests/compiler/dart2js_native/native_call_arity2_frog_test.dart
+++ b/tests/compiler/dart2js_native/native_call_arity2_frog_test.dart
@@ -20,30 +20,33 @@ class B extends A {
 makeA() native;
 makeB() native;
 
-void setup() native """
-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() {}
-A.prototype.foo = function () { return arguments.length; };
+  function A() {}
+  A.prototype.foo = function () { return arguments.length; };
 
-function B() {}
-B.prototype.foo = function () { return arguments.length; };
-inherits(B, A);
+  function B() {}
+  B.prototype.foo = function () { return arguments.length; };
+  inherits(B, A);
 
-makeA = function(){return new A;};
-makeB = function(){return new B;};
+  makeA = function(){return new A()};
+  makeB = function(){return new B()};
 
-self.nativeConstructor(A);
-self.nativeConstructor(B);
-""";
+  self.nativeConstructor(A);
+  self.nativeConstructor(B);
+})()""");
+}
 
 testDynamicContext() {
   var a = confuse(makeA());