Fix a bunch of pub tests that started running "pub get".

test/dart2js/supports_valid_options_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.
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import '../serve/utils.dart';
 
@@ skipping 17 matching lines @@
             "sourceMaps": false
           }
         }]
       }),
       d.dir("web", [
         d.file("main.dart", "void main() => print('Hello!');")
       ])
     ]).create();
 
     // None of these options should be rejected, either by pub or by dart2js.
-    pubServe();
+    pubServe(shouldGetFirst: true);
     requestShouldSucceed("main.dart.js", isNot(isEmpty));
     endPubServe();
   });
 }