Support dart2js in pub serve.

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 'package:http/http.dart' as http;
 import 'package:scheduled_test/scheduled_process.dart';
@@ skipping 102 matching lines @@
   var match = new RegExp(r"127\.0\.0\.1:(\d+)").firstMatch(line);
   assert(match != null);
   _port = int.parse(match[1]);
 }
 
 void endPubServe() {
   _pubServer.kill();
 }
 
 /// Schedules an HTTP request to the running pub server with [urlPath] and
-/// verifies that it responds with [expected].
-void requestShouldSucceed(String urlPath, String expected) {
+/// verifies that it responds with a body that matches [expectation].
+///
+/// [expectation] may either be a [Matcher] or a string to match an exact body.
+void requestShouldSucceed(String urlPath, expectation) {
   schedule(() {
     return http.get("http://127.0.0.1:$_port/$urlPath").then((response) {
-      expect(response.body, equals(expected));
+      expect(response.body, expectation);
     });
   }, "request $urlPath");
 }
 
 /// Schedules an HTTP request to the running pub server with [urlPath] and
 /// verifies that it responds with a 404.
 void requestShould404(String urlPath) {
   schedule(() {
     return http.get("http://127.0.0.1:$_port/$urlPath").then((response) {
       expect(response.statusCode, equals(404));
@@ skipping 21 matching lines @@
     return _pubServer.nextLine().then((line) {
       if (line.contains("successfully")) return;
 
       // This line wasn't it, so ignore it and keep trying.
       return nextLine();
     });
   }
 
   schedule(nextLine);
 }