Add library tags to allow Dartium to run the crypto tests.

tests/lib/crypto/sha256_test.dart

Index: tests/lib/crypto/sha256_test.dart
diff --git a/tests/lib/crypto/sha256_test.dart b/tests/lib/crypto/sha256_test.dart
index 36d7ecafe60a0982cbd5edcf602e07165275fd3a..588cc575f295c335be40c2b59a48b8e8b76363b9 100644
--- a/tests/lib/crypto/sha256_test.dart
+++ b/tests/lib/crypto/sha256_test.dart
@@ -2,7 +2,9 @@
 // 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('sha256Test');
+// Library tag to allow Dartium to run the tests.
+#library('sha256_test');
+
 // TODO(ager): Replace with "dart:crypto" when ready.
 #import("../../../lib/crypto/crypto.dart");