Fix dart2js tests in pub.

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

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 242 matching lines @@
 }
 
 /// Schedules an HTTP request to the running pub server with [urlPath] and
 /// verifies that it responds with a body that matches [expectation].
 ///
 /// [expectation] may either be a [Matcher] or a string to match an exact body.
 /// [root] indicates which server should be accessed, and defaults to "web".
 /// [headers] may be either a [Matcher] or a map to match an exact headers map.
 void requestShouldSucceed(String urlPath, expectation, {String root, headers}) {
   scheduleRequest(urlPath, root: root).then((response) {
+    expect(response.statusCode, equals(200));
     if (expectation != null) expect(response.body, expectation);
     if (headers != null) expect(response.headers, headers);
   });
 }
 
 /// Schedules an HTTP request to the running pub server with [urlPath] and
 /// verifies that it responds with a 404.
 ///
 /// [root] indicates which server should be accessed, and defaults to "web".
 void requestShould404(String urlPath, {String root}) {
@@ skipping 217 matching lines @@
 /// included. Unlike [getServerUrl], this should only be called after the ports
 /// are known.
 String _getServerUrlSync([String root, String path]) {
   if (root == null) root = 'web';
   expect(_ports, contains(root));
   var url = "http://localhost:${_ports[root]}";
   if (path != null) url = "$url/$path";
   return url;
 }