Use shelf handlers in ScheduledServer.

sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_test.dart

Index: sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_test.dart
diff --git a/sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_test.dart b/sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_test.dart
index d83570a9daebae77750b505e535e2fc25e3fa18a..fc39458a3402de5adc9fd10ac7843d0d98c10b6a 100644
--- a/sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_test.dart
+++ b/sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_test.dart
@@ -4,6 +4,7 @@
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
+import 'package:shelf/shelf.dart' as shelf;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
@@ -19,10 +20,10 @@ main() {
     confirmPublish(pub);
 
     server.handle('GET', '/api/packages/versions/new', (request) {
-      expect(request.headers.value('authorization'),
-          equals('Bearer access token'));
+      expect(request.headers,
+          containsPair('authorization', 'Bearer access token'));
 
-      request.response.close();
+      return new shelf.Response(200);
     });
 
     pub.kill();