Get rid of all the library tags.

test/transformer/exclusion/exclude_asset_string_test.dart

Index: test/transformer/exclusion/exclude_asset_string_test.dart
diff --git a/test/transformer/exclusion/exclude_asset_string_test.dart b/test/transformer/exclusion/exclude_asset_string_test.dart
index ad46e38357978dda3ff09dc62fe6ed54bda20568..3f8b6cd87820fd30edf4c8522aa624ed0a2f2974 100644
--- a/test/transformer/exclusion/exclude_asset_string_test.dart
+++ b/test/transformer/exclusion/exclude_asset_string_test.dart
@@ -2,8 +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 pub_tests;
-
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import '../../serve/utils.dart';