Remove some more library directives

pkg/analysis_server/benchmark/perf/benchmark_flutter.dart

Index: pkg/analysis_server/benchmark/perf/benchmark_flutter.dart
diff --git a/pkg/analysis_server/benchmark/perf/benchmark_flutter.dart b/pkg/analysis_server/benchmark/perf/benchmark_flutter.dart
index b05b9f8eebcadb16166699fa5b14c8ae8335bf71..2e47a2b3bf8bd828d01db062c954efdfb704108c 100644
--- a/pkg/analysis_server/benchmark/perf/benchmark_flutter.dart
+++ b/pkg/analysis_server/benchmark/perf/benchmark_flutter.dart
@@ -2,8 +2,6 @@
 // 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 server.performance.local;
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol_generated.dart';