Revert "Add native_testing library to mock @Native classes"

tests/compiler/dart2js_native/native_field_invocation5_test.dart

Index: tests/compiler/dart2js_native/native_field_invocation5_test.dart
diff --git a/tests/compiler/dart2js_native/native_field_invocation5_test.dart b/tests/compiler/dart2js_native/native_field_invocation5_test.dart
index 5c3ff7b6e05625c8ff91f4c76ec14f725cb14a1d..abc60aad90a0c2bd48f0b1d0d87e85f3c5a44dcf 100644
--- a/tests/compiler/dart2js_native/native_field_invocation5_test.dart
+++ b/tests/compiler/dart2js_native/native_field_invocation5_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";
 
 makeCC() native ;
 nativeFirst(x, y) native ;
@@ -11,7 +12,6 @@ void setup() native """
 function CC() {}
 makeCC = function() { return new CC; }
 nativeFirst = function(x, y) { return x; }
-self.nativeConstructor(CC);
 """;
 
 class C {
@@ -38,7 +38,6 @@ wrap(cb) {
 }
 
 main() {
-  nativeTesting();
   setup();
   var c = makeCC();
   c.init();