Add mirrors tests

test/codegen/lib/mirrors/library_imports_metadata.dart

Index: test/codegen/lib/mirrors/library_imports_metadata.dart
diff --git a/test/codegen/language/async_backwards_compatibility_1_test.dart b/test/codegen/lib/mirrors/library_imports_metadata.dart
similarity index 56%
copy from test/codegen/language/async_backwards_compatibility_1_test.dart
copy to test/codegen/lib/mirrors/library_imports_metadata.dart
index 93908797af9400f0cdc751626158e1f4e39f6af5..9507269f47568c6d06a92b099330c183aaaa9ef4 100644
--- a/test/codegen/language/async_backwards_compatibility_1_test.dart
+++ b/test/codegen/lib/mirrors/library_imports_metadata.dart
@@ -2,17 +2,16 @@
 // 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 'dart:async';
-import 'async_helper_lib.dart' as async;
+library library_imports_metadata;
+
+@m1
+import 'dart:mirrors' as mirrors;
 
-class A {
-  async.async get async => null;
-}
+@m2 @m3
+import 'dart:collection';
 
-async.async topLevel() => null;
+import 'dart:async';
 
-main() {
-  var a = new A();
-  var b = a.async;
-  var c = topLevel();
-}
+const m1 = const Object();
+const m2 = const Object();
+const m3 = const Object();