Remove --harmony-arrow-functions flag

test/mjsunit/strong/mutually-recursive-classes.js

 // 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: --strong-mode --harmony-arrow-functions
+// Flags: --strong-mode
 "use strict"
 
 let prologue_dead = "(function outer() { if (false) { ";
 let epilogue_dead = " } })();";
 
 let prologue_live = "(function outer() { ";
 let epilogue_live = "})();";
 
 // For code which already throws a run-time error in non-strong mode; we assert
 // that we now get the error already compilation time.
@@ skipping 204 matching lines @@
   ;
 
   class A2 {
     m() {
       class C2 extends B2 {
       }
     }
   }
   class B2 { }
 })();