Remove all harmony runtime flags which shipped in M51

test/mjsunit/es6/iterator-close.js

 // Copyright 2016 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-iterator-close
-
 
 function* g() { yield 42; return 88 };
 
 
 // Return method is "undefined".
 {
   g.prototype.return = null;
 
 
   assertEquals(undefined, (() => {
@@ skipping 1346 matching lines @@
   })());
 
   assertEquals(42, (() => {
     for (let x of g()) return 42;
   })());
 
   assertThrowsEquals(() => {
     for (let x of g()) throw 42;
   }, 42);
 }