Get rid of all the library tags.

test/snapshot/doesnt_load_irrelevant_transformers_test.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_tests;
-
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 const BROKEN_TRANSFORMER = """
 import 'dart:async';
 
 import 'package:barback/barback.dart';
@@ skipping 37 matching lines @@
 
     d.dir(p.join(appPath, '.pub', 'bin'), [
       d.dir('foo', [d.matcherFile('hello.dart.snapshot', contains('hello!'))])
     ]).validate();
 
     var process = pubRun(args: ['foo:hello']);
     process.stdout.expect("hello!");
     process.shouldExit();
   });
 }