Use shelf in pub's barback and admin servers.

sdk/lib/_internal/pub/test/lish/utils.dart

 // Copyright (c) 2013, 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 lish.utils;
 
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:shelf/shelf.dart' as shelf;
 
 import '../../lib/src/io.dart';
 
 void handleUploadForm(ScheduledServer server, [Map body]) {
   server.handle('GET', '/api/packages/versions/new', (request) {
     return server.url.then((url) {
@@ skipping 19 matching lines @@
 void handleUpload(ScheduledServer server) {
   server.handle('POST', '/upload', (request) {
     // TODO(nweiz): Once a multipart/form-data parser in Dart exists, validate
     // that the request body is correctly formatted. See issue 6952.
     return drainStream(request.read())
         .then((_) => server.url)
         .then((url) => new shelf.Response.found(url.resolve('/create')));
   });
 }