Rip out the last dart:io dependency from pkg/http.

pkg/http/test/io/client_test.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// 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 client_test;
+library http.test.io.client_test;
 
 import 'dart:io';
 
 import 'package:http/http.dart' as http;
 import 'package:unittest/unittest.dart';
 
 import 'utils.dart';
 
 void main() {
   tearDown(stopServer);
@@ skipping 40 matching lines @@
       request.headers[HttpHeaders.CONTENT_TYPE] =
           'application/json; charset=utf-8';
 
       expect(client.send(request), throwsSocketException);
 
       request.sink.add('{"hello": "world"}'.codeUnits);
       request.sink.close();
     }), completes);
   });
 }