Access to imports in the VM's runtime mirrors. Extend test coverage of the source mirrors.

tests/lib/mirrors/library_imports_metadata.dart

Index: tests/lib/mirrors/library_imports_metadata.dart
diff --git a/tests/lib/mirrors/library_imports_metadata.dart b/tests/lib/mirrors/library_imports_metadata.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9507269f47568c6d06a92b099330c183aaaa9ef4
--- /dev/null
+++ b/tests/lib/mirrors/library_imports_metadata.dart
@@ -0,0 +1,17 @@
+// 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.
+
+library library_imports_metadata;
+
+@m1
+import 'dart:mirrors' as mirrors;
+
+@m2 @m3
+import 'dart:collection';
+
+import 'dart:async';
+
+const m1 = const Object();
+const m2 = const Object();
+const m3 = const Object();