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

test/mjsunit/harmony/rest-params-lazy-parsing.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
-// Flags: --min-preparse-length=0
-
-function variadic(co, ...values) {
-  var sum = 0;
-  while (values.length) {
-    sum += co * values.pop();
-  }
-  return sum;
-}
-
-var arrowVariadic = (co, ...values) => {
-  var sum = 0;
-  while (values.length) {
-    sum += co * values.pop();
-  }
-  return sum;
-}
-
-assertEquals(1, variadic.length);
-assertEquals(1, arrowVariadic.length);
-
-assertEquals(90, variadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9));
-assertEquals(74, variadic(2, 1, 2, 3, 4, 5, 6, 7, 9));
-assertEquals(110, variadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
-
-assertEquals(90, arrowVariadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9));
-assertEquals(74, arrowVariadic(2, 1, 2, 3, 4, 5, 6, 7, 9));
-assertEquals(110, arrowVariadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));