Remove runtime flags for Proxy and Reflect

test/mjsunit/es6/proxies-set-prototype-of.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
-
 var target = { target: 1 };
 target.__proto__ = {};
 var handler = { handler: 1 };
 var proxy = new Proxy(target, handler);
 
 assertSame(Object.getPrototypeOf(proxy), target.__proto__ );
 
 
 assertThrows(function() { Object.setPrototypeOf(proxy, undefined) }, TypeError);
 assertThrows(function() { Object.setPrototypeOf(proxy, 1) }, TypeError);
@@ skipping 104 matching lines @@
   assertThrows(() => {Reflect.setPrototypeOf(proxy2, prototype)}, TypeError);
 })();
 
 (function testProxyTrapReturnsFalse() {
   var handler = {};
   handler.setPrototypeOf = () => false;
   var target = new Proxy({}, {isExtensible: () => assertUnreachable()});
   var object = new Proxy(target, handler);
   assertFalse(Reflect.setPrototypeOf(object, {}));
 })();