Remove --harmony-arrow-functions flag

test/mjsunit/es6/arrow-functions-lexical-arguments.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: --harmony-arrow-functions
-
 
 (function testInFunctionDeclaration() {
   var calls = 0;
   function f() {
     (() => {
       calls++;
       assertEquals(2, arguments.length);
       assertEquals('a', arguments[0]);
       assertEquals('b', arguments[1]);
     })();
@@ skipping 132 matching lines @@
   var calls = 0;
   function f(arguments) {
     (() => {
       calls++;
       assertEquals('a', arguments);
     })();
   }
   f('a');
   assertEquals(1, calls);
 })();