Add tests for simple packages scenarios

tests/standalone/package/scenarios/packages_dir_only/packages/foo/foo.dart

Index: tests/standalone/package/scenarios/packages_dir_only/packages/foo/foo.dart
diff --git a/tests/lib/mirrors/typedef_library.dart b/tests/standalone/package/scenarios/packages_dir_only/packages/foo/foo.dart
similarity index 86%
copy from tests/lib/mirrors/typedef_library.dart
copy to tests/standalone/package/scenarios/packages_dir_only/packages/foo/foo.dart
index fcb3231612c0219e91e8b17b9983f6576c20f351..87b2fe16c76f8074b9bd1878e11504839a99ee44 100644
--- a/tests/lib/mirrors/typedef_library.dart
+++ b/tests/standalone/package/scenarios/packages_dir_only/packages/foo/foo.dart
@@ -2,6 +2,6 @@
 // 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 bar;
+library foo;
 
-typedef G();
+String bar = 'hello';