Add failing (for dart2js) deferred constant-list test.

tests/language/deferred_constant_list_lib.dart

Index: tests/language/deferred_constant_list_lib.dart
diff --git a/pkg/docgen/test/multi_library_code/lib/test_lib2_bar.dart b/tests/language/deferred_constant_list_lib.dart
similarity index 74%
copy from pkg/docgen/test/multi_library_code/lib/test_lib2_bar.dart
copy to tests/language/deferred_constant_list_lib.dart
index 1a07d2bfcbec000ca259946fd3598f181039ec0b..93a674084dce9d53a32badd7c4f73529e297d1ef 100644
--- a/pkg/docgen/test/multi_library_code/lib/test_lib2_bar.dart
+++ b/tests/language/deferred_constant_list_lib.dart
@@ -2,8 +2,5 @@
 // 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 test_lib2_bar;
-
-class Bar {
-
-}
+final finalConstList = const [1, 2];
+var nonFinalConstList = const [3, 4];