Revert "Add native_testing library to mock @Native classes"

tests/compiler/dart2js_native/native_class_avoids_hidden_name_frog_test.dart

Index: tests/compiler/dart2js_native/native_class_avoids_hidden_name_frog_test.dart
diff --git a/tests/compiler/dart2js_native/native_class_avoids_hidden_name_frog_test.dart b/tests/compiler/dart2js_native/native_class_avoids_hidden_name_frog_test.dart
index 3f286822d7304c01f0696579be69a63ffa78bfee..8690e4b856605d04c7a158b4e22c72d49e67fdd0 100644
--- a/tests/compiler/dart2js_native/native_class_avoids_hidden_name_frog_test.dart
+++ b/tests/compiler/dart2js_native/native_class_avoids_hidden_name_frog_test.dart
@@ -2,7 +2,8 @@
 // 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";
+import "dart:_js_helper";
+import "package:expect/expect.dart";
 
 // Test that hidden native class names are not used by generated code.
 
@@ -40,18 +41,18 @@ function BB(){}
 function CC(){}
 makeA = function(){return new BB};  // AA is native "BB"
 makeB = function(){return new CC};  // BB is native "CC"
-self.nativeConstructor(BB);
-self.nativeConstructor(CC);
 """;
 
+int inscrutable(int x) => x == 0 ? 0 : x | inscrutable(x & (x - 1));
+
 main() {
-  nativeTesting();
   setup1();
   setup2();
 
-  var a = confuse(AA.create());
-  var b = confuse(BB.create());
-  var c = confuse(CC.create());
+  var things = [AA.create(), BB.create(), CC.create()];
+  var a = things[inscrutable(0)];
+  var b = things[inscrutable(1)];
+  var c = things[inscrutable(2)];
 
   Expect.equals('AA', a.name);
   Expect.equals('BB', b.name);