Fix the old-hijack test.

lib/src/request.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.
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:http_parser/http_parser.dart';
 import 'package:stream_channel/stream_channel.dart';
 
@@ skipping 228 matching lines @@
   ///
   /// This may only be called when using a Shelf adapter that supports
   /// hijacking, such as the `dart:io` adapter. In addition, a given request may
   /// only be hijacked once. [canHijack] can be used to detect whether this
   /// request can be hijacked.
   void hijack(Function callback) {
     if (_onHijack == null) {
       throw new StateError("This request can't be hijacked.");
     }
 
-    if (callback is ZoneUnaryCallback) {
+    if (callback is! ZoneBinaryCallback) {
       var oldCallback = callback;
       callback = (stream, sink) {
         oldCallback(new StreamChannel<List<int>>(stream, sink));
       };
     }
 
     _onHijack.run(callback);
     throw const HijackException();
   }
 }
@@ skipping 94 matching lines @@
     return handlerPath;
   } else if (url != null) {
     if (url.path.isEmpty) return requestedUri.path;
 
     var index = requestedUri.path.indexOf(url.path);
     return requestedUri.path.substring(0, index);
   } else {
     return '/';
   }
 }