Fix native extension lookup

tests/standalone/io/test_relative_extension_fail_tester.dart

Index: tests/standalone/io/test_relative_extension_fail_tester.dart
diff --git a/tests/standalone/io/test_extension_fail_tester.dart b/tests/standalone/io/test_relative_extension_fail_tester.dart
similarity index 85%
copy from tests/standalone/io/test_extension_fail_tester.dart
copy to tests/standalone/io/test_relative_extension_fail_tester.dart
index f2e72aeca5e4732e02af7ad4c3c918dc1b60c7a7..ad37cf09dd610f87db52065cde9f2e9e8c6e9f8f 100644
--- a/tests/standalone/io/test_extension_fail_tester.dart
+++ b/tests/standalone/io/test_relative_extension_fail_tester.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2016, 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.
 
@@ -6,7 +6,7 @@ library test_extension_test;
 
 import "dart:async";
 import "dart:isolate";
-import "test_extension.dart";
+import "test_relative_extension.dart";
 
 main() {
   try {