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

tests/compiler/dart2js_native/native_call_arity3_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";
 
 // Test similar to NativeCallArity1FrogTest, but with default values to
 // parameters set to null. These parameters should be treated as if they
 // do not have a default value for the native methods.
 
 @Native("A")
 class A {
   int foo(int x) native;
 }
 
 @Native("B")
 class B {
   int foo([x = null, y, z = null]) native;
 }
 
 // TODO(sra): Add a case where the parameters have default values.  Wait until
 // dart:html need non-null default values.
 
 A makeA() native;
 B makeB() native;
 
-void setup() native """
-function A() {}
-A.prototype.foo = function () { return arguments.length; };
+void setup() {
+  JS('', r"""
+(function(){
+  function A() {}
+  A.prototype.foo = function () { return arguments.length; };
 
-function B() {}
-B.prototype.foo = function () { return arguments.length; };
+  function B() {}
+  B.prototype.foo = function () { return arguments.length; };
 
-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());
   var b = confuse(makeB());
 
   Expect.throws(() => a.foo());
   Expect.equals(1, a.foo(10));
   Expect.throws(() => a.foo(10, 20));
   Expect.throws(() => a.foo(10, 20, 30));
 
@@ skipping 27 matching lines @@
   Expect.equals(3, b.foo(null, null, 30));
   Expect.throws(() => b.foo(10, 20, 30, 40));
 }
 
 main() {
   nativeTesting();
   setup();
   testDynamicContext();
   testStaticContext();
 }