Remove always-on --harmony-rest-parameters flag

test/mjsunit/es6/rest-params.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.
 
-// Flags: --harmony-rest-parameters
-
 (function testRestIndex() {
   assertEquals(5, (function(...args) { return args.length; })(1,2,3,4,5));
   assertEquals(4, (function(a, ...args) { return args.length; })(1,2,3,4,5));
   assertEquals(3, (function(a, b, ...args) { return args.length; })(1,2,3,4,5));
   assertEquals(2, (function(a, b, c, ...args) {
                       return args.length; })(1,2,3,4,5));
   assertEquals(1, (function(a, b, c, d, ...args) {
                       return args.length; })(1,2,3,4,5));
   assertEquals(0, (function(a, b, c, d, e, ...args) {
                     return args.length; })(1,2,3,4,5));
@@ skipping 195 matching lines @@
     function(){ eval("(class{foo(...rest) {'use strict';}});") }, SyntaxError);
 
   assertThrows(
     function(){ eval("function(a, ...rest){'use strict';}") }, SyntaxError);
   assertThrows(
     function(){ eval("(a, ...rest) => {'use strict';}") }, SyntaxError);
   assertThrows(
     function(){ eval("(class{foo(a, ...rest) {'use strict';}});") },
     SyntaxError);
 })();