Remove runtime flags for Proxy and Reflect

test/mjsunit/harmony/proxies-revocable.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-proxies --harmony-reflect
-
-
-traps = [
-    "getPrototypeOf", "setPrototypeOf", "isExtensible", "preventExtensions",
-    "getOwnPropertyDescriptor", "has", "get", "set", "deleteProperty",
-    "defineProperty", "ownKeys", "apply", "construct"
-];
-
-var {proxy, revoke} = Proxy.revocable({}, {});
-assertEquals(0, revoke.length);
-
-assertEquals(undefined, revoke());
-for (var trap of traps) {
-  assertThrows(() => Reflect[trap](proxy), TypeError);
-}
-
-assertEquals(undefined, revoke());
-for (var trap of traps) {
-  assertThrows(() => Reflect[trap](proxy), TypeError);
-}