Get rid of all the library tags.

lib/src/handle_access_token_response.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 oauth2.handle_access_token_response;
-
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;
 import 'package:http_parser/http_parser.dart';
 
 import 'credentials.dart';
 import 'authorization_exception.dart';
 
 /// The amount of time to add as a "grace period" for credential expiration.
 ///
@@ skipping 120 matching lines @@
 
 void _validate(
     http.Response response,
     Uri tokenEndpoint,
     bool condition,
     String message) {
   if (condition) return;
   throw new FormatException('Invalid OAuth response for "$tokenEndpoint": '
       '$message.\n\n${response.body}');
 }