remove duplicate packages in fuzz test

pkg/analysis_server/bin/fuzz/json.dart

Index: pkg/analysis_server/bin/fuzz/json.dart
diff --git a/pkg/analysis_server/bin/fuzz/json.dart b/pkg/analysis_server/bin/fuzz/json.dart
deleted file mode 100644
index 462bea826462b4aca0b825fd57be5404a2b50d11..0000000000000000000000000000000000000000
--- a/pkg/analysis_server/bin/fuzz/json.dart
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS 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 services.json;
-
-/**
- * Instances of the class [HasToJson] implement [toJson] method that returns
- * a JSON presentation.
- */
-abstract class HasToJson {
-  /**
-   * Returns a JSON presentation of the object.
-   */
-  Map<String, Object> toJson();
-}