Get rid of all the library tags.

lib/src/runner/browser/firefox.dart

 // Copyright (c) 2015, 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 test.runner.browser.firefox;
-
 import 'dart:async';
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 
 import '../../util/io.dart';
 import 'browser.dart';
 
 final _preferences = '''
 user_pref("browser.shell.checkDefaultBrowser", false);
@@ skipping 59 matching lines @@
 
       var path = p.join(prefix, suffix);
       if (new File(p.join(prefix, suffix)).existsSync()) return path;
     }
 
     // Fall back on looking it up on the path. This probably won't work, but at
     // least it will fail with a useful error message.
     return "firefox.exe";
   }
 }