Move package:testing to SDK.

pkg/testing/test/hello_test.dart

Index: pkg/testing/test/hello_test.dart
diff --git a/pkg/testing/test/hello_test.dart b/pkg/testing/test/hello_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..671d11fb0e48ac8badee6ba7b447e0a6990de757
--- /dev/null
+++ b/pkg/testing/test/hello_test.dart
@@ -0,0 +1,7 @@
+// 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.md file.
+
+main() {
+  print("Hello, World!");
+}