Remove runtime flags for Proxy and Reflect

test/mjsunit/es6/proxies-cross-realm-exception.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 --allow-natives-syntax
+// Flags: --allow-natives-syntax
 
 // Do not read out the prototype from a cross-realm object.
 var realm = Realm.create();
 
 __proto__ = {};
 assertEquals(null,
   Realm.eval(realm, "3; Reflect.getPrototypeOf(Realm.global(0))"));
 assertFalse(Realm.eval(realm, "3; Realm.global(0) instanceof Object"));
 
 __proto__ = new Proxy({}, { getPrototypeOf() { assertUnreachable() } });
@@ skipping 28 matching lines @@
 // 2-level proxy indirection
 __proto__ = {};
 __proto__ = new Proxy({},
   new Proxy({}, {
     get() { assertUnreachable() }
   })
 );
 assertEquals(null,
   Realm.eval(realm, "5; Reflect.getPrototypeOf(Realm.global(0))"));
 assertFalse(Realm.eval(realm, "5; Realm.global(0) instanceof Object"));