Get rid of all the library tags.

lib/src/source/unknown.dart

 // Copyright (c) 2014, 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.source.unknown;
-
 import 'dart:async';
 
 import 'package:pub_semver/pub_semver.dart';
 
 import '../package.dart';
 import '../pubspec.dart';
 import '../source.dart';
 
 /// A [Null Object] that represents a source not recognized by pub.
 ///
@@ skipping 29 matching lines @@
 
   bool descriptionsEqual(description1, description2) =>
       description1 == description2;
 
   PackageRef parseRef(String name, description, {String containingPath}) =>
       new PackageRef(name, this.name, description);
 
   PackageId parseId(String name, Version version, description) =>
       new PackageId(name, this.name, version, description);
 }