Don't implicitly run "pub get".

test/dart2js/converts_isolate_entrypoint_in_web_test.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.
 
 // Dart2js can take a long time to compile dart code, so we increase the timeout
 // to cope with that.
 @Timeout.factor(3)
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import '../serve/utils.dart';
 
 main() {
   integration("converts a Dart isolate entrypoint in web to JS", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir("web", [
         d.file("isolate.dart", "void main(List<String> args, SendPort "
             "sendPort) => print('hello');")
       ])
     ]).create();
 
-    pubServe(shouldGetFirst: true);
+    pubGet();
+    pubServe();
     requestShouldSucceed("isolate.dart.js", contains("hello"));
     endPubServe();
   });
 }