Remove --harmony-for-in flag which is always false

test/mjsunit/harmony/for-in.js

Index: test/mjsunit/harmony/for-in.js
diff --git a/test/mjsunit/harmony/for-in.js b/test/mjsunit/harmony/for-in.js
deleted file mode 100644
index 58e343b90355bbd8ad022463a18497d095e387c3..0000000000000000000000000000000000000000
--- a/test/mjsunit/harmony/for-in.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// Copyright 2015 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Flags: --harmony-for-in
-
-assertThrows("for (var x = 0 in {});", SyntaxError);
-assertThrows("for (const x = 0 in {});", SyntaxError);
-assertThrows("for (let x = 0 in {});", SyntaxError);