Add native_testing library to mock @Native classes

tests/compiler/dart2js_native/subclassing_5_test.dart

 // Copyright (c) 2013, 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 "package:expect/expect.dart";
-import 'dart:_js_helper' show Native, Creates, setNativeSubclassDispatchRecord;
+import 'native_testing.dart';
+import 'dart:_js_helper' show setNativeSubclassDispatchRecord;
 import 'dart:_interceptors' show Interceptor, findInterceptorForType;
 
 // Test type checks.
 
 class I {}
 
 class M implements I {
   miz() => 'M';
 }
 
@@ skipping 97 matching lines @@
 testCastA(x) {
   var z = x as A;
   Expect.identical(x, z);
 }
 
 testCastB(x) {
   var z = x as B;
   Expect.identical(x, z);
 }
 
-var inscrutable;
-
 main() {
+  nativeTesting();
   setup();
-  inscrutable = (x) => x;
 
   setNativeSubclassDispatchRecord(getBPrototype(), findInterceptorForType(B));
 
-  var b = inscrutable(makeB());
+  var b = confuse(makeB());
 
-  inscrutable(testIsB)(b);
-  inscrutable(testIsA)(b);
-  inscrutable(testIsN)(b);
-  inscrutable(testIsM)(b);
-  inscrutable(testIsI)(b);
+  confuse(testIsB)(b);
+  confuse(testIsA)(b);
+  confuse(testIsN)(b);
+  confuse(testIsM)(b);
+  confuse(testIsI)(b);
 
-  inscrutable(new Checks<B>().isCheck)(b);
-  inscrutable(new Checks<A>().isCheck)(b);
-  inscrutable(new Checks<N>().isCheck)(b);
-  inscrutable(new Checks<M>().isCheck)(b);
-  inscrutable(new Checks<I>().isCheck)(b);
+  confuse(new Checks<B>().isCheck)(b);
+  confuse(new Checks<A>().isCheck)(b);
+  confuse(new Checks<N>().isCheck)(b);
+  confuse(new Checks<M>().isCheck)(b);
+  confuse(new Checks<I>().isCheck)(b);
 
   if (isCheckedMode()) {
-    inscrutable(testAssignB)(b);
-    inscrutable(testAssignA)(b);
-    inscrutable(testAssignN)(b);
-    inscrutable(testAssignM)(b);
-    inscrutable(testAssignI)(b);
+    confuse(testAssignB)(b);
+    confuse(testAssignA)(b);
+    confuse(testAssignN)(b);
+    confuse(testAssignM)(b);
+    confuse(testAssignI)(b);
 
-    inscrutable(testCastB)(b);
-    inscrutable(testCastA)(b);
-    inscrutable(testCastN)(b);
-    inscrutable(testCastM)(b);
-    inscrutable(testCastI)(b);
+    confuse(testCastB)(b);
+    confuse(testCastA)(b);
+    confuse(testCastN)(b);
+    confuse(testCastM)(b);
+    confuse(testCastI)(b);
 
-    inscrutable(new Checks<B>().assignCheck)(b);
-    inscrutable(new Checks<A>().assignCheck)(b);
-    inscrutable(new Checks<N>().assignCheck)(b);
-    inscrutable(new Checks<M>().assignCheck)(b);
-    inscrutable(new Checks<I>().assignCheck)(b);
+    confuse(new Checks<B>().assignCheck)(b);
+    confuse(new Checks<A>().assignCheck)(b);
+    confuse(new Checks<N>().assignCheck)(b);
+    confuse(new Checks<M>().assignCheck)(b);
+    confuse(new Checks<I>().assignCheck)(b);
 
-    inscrutable(new Checks<B>().castCheck)(b);
-    inscrutable(new Checks<A>().castCheck)(b);
-    inscrutable(new Checks<N>().castCheck)(b);
-    inscrutable(new Checks<M>().castCheck)(b);
-    inscrutable(new Checks<I>().castCheck)(b);
+    confuse(new Checks<B>().castCheck)(b);
+    confuse(new Checks<A>().castCheck)(b);
+    confuse(new Checks<N>().castCheck)(b);
+    confuse(new Checks<M>().castCheck)(b);
+    confuse(new Checks<I>().castCheck)(b);
   }
 }