Adding package:smoke. This CL includes the intial APIs, a mirror-based

pkg/smoke/test/mirrors_test.dart

 // Copyright (c) 2014, 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.
 
-// Regression test for issue 16640.
+library smoke.test.mirrors_test;
 
-class Segment extends SegmentGen { }
-
-class SegmentGen extends ConceptEntity<Segment> { }
-
-class ConceptEntity<E> { }
+import 'package:smoke/mirrors.dart';
+import 'package:unittest/unittest.dart';
+import 'common.dart' as common show main;
 
 main() {
-  new ConceptEntity<Segment>();
+  setUp(useMirrors);
+  common.main();
 }