Get rid of all the library tags.

lib/src/util.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 shelf.util;
-
 import 'dart:async';
 
 /// Like [new Future], but avoids around issue 11911 by using [new Future.value]
 /// under the covers.
 Future newFuture(callback()) => new Future.value().then((_) => callback());
 
 /// Run [callback] and capture any errors that would otherwise be top-leveled.
 ///
 /// If [this] is called in a non-root error zone, it will just run [callback]
 /// and return the result. Otherwise, it will capture any errors using
@@ skipping 21 matching lines @@
 
 /// Adds a header with [name] and [value] to [headers], which may be null.
 ///
 /// Returns a new map without modifying [headers].
 Map<String, String> addHeader(
     Map<String, String> headers, String name, String value) {
   headers = headers == null ? {} : new Map.from(headers);
   headers[name] = value;
   return headers;
 }