Get rid of all the library tags.

lib/src/validator/directory.dart

 // Copyright (c) 2012, 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 pub.validator.directory;
-
 import 'dart:async';
 
 import 'package:path/path.dart' as path;
 
 import '../entrypoint.dart';
 import '../io.dart';
 import '../validator.dart';
 
 /// A validator that validates a package's top-level directories.
 class DirectoryValidator extends Validator {
@@ skipping 23 matching lines @@
 
         if (dir.contains(new RegExp(r"^samples?$"))) {
           warnings.add('Rename the top-level "$dir" directory to "example".\n'
               'This allows Pub to find your examples and create "packages" '
                   'directories for them.\n');
         }
       }
     });
   }
 }