Remove stale references to --harmony-arrays flag in mjsunit tests

test/mjsunit/es6/array-of.js

 // Copyright 2014 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.
 
 // Based on Mozilla Array.of() tests at http://dxr.mozilla.org/mozilla-central/source/js/src/jit-test/tests/collections
 
-// Flags: --harmony-arrays
-
 
 
 // Array.of makes real arrays.
 
 function check(a) {
     assertEquals(Object.getPrototypeOf(a), Array.prototype);
     assertEquals(Array.isArray(a), true);
     a[9] = 9;
     assertEquals(a.length, 10);
 }
@@ skipping 186 matching lines @@
   assertEquals(1, xlength.value);
   assertEquals(true, xlength.writable);
   assertEquals(true, xlength.enumerable);
   assertEquals(true, xlength.configurable);
   var x0 = Object.getOwnPropertyDescriptor(x, 0);
   assertEquals(2, x0.value);
   assertEquals(true, xlength.writable);
   assertEquals(true, xlength.enumerable);
   assertEquals(true, xlength.configurable);
 })();