Add native_testing library to mock @Native classes

tests/compiler/dart2js_native/super_call_test.dart

Index: tests/compiler/dart2js_native/super_call_test.dart
diff --git a/tests/compiler/dart2js_native/super_call_test.dart b/tests/compiler/dart2js_native/super_call_test.dart
index b42051645488d1542af30da3442ca90c02b93b16..0a880f39ca6b9c618dbdd11351e9663224f23951 100644
--- a/tests/compiler/dart2js_native/super_call_test.dart
+++ b/tests/compiler/dart2js_native/super_call_test.dart
@@ -2,8 +2,7 @@
 // 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 "dart:_js_helper";
-import "package:expect/expect.dart";
+import "native_testing.dart";
 
 // Test to see if resolving a hidden native class's method interferes with
 // subsequent resolving the subclass's method.  This might happen if the
@@ -62,9 +61,15 @@ makeA = function(){return new A};
 makeB = function(){return new B};
 makeC = function(){return new C};
 makeD = function(){return new D};
+
+self.nativeConstructor(A);
+self.nativeConstructor(B);
+self.nativeConstructor(C);
+self.nativeConstructor(D);
 """;
 
 main() {
+  nativeTesting();
   setup();
 
   var a = makeA();