Remove runtime flags for Proxy and Reflect

test/mjsunit/harmony/proxies-keys.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
-
-var target = {
-  target: 1
-};
-target.__proto__ = {
-  target_proto: 2
-};
-
-var handler = {
-  ownKeys: function(target) {
-    return ["foo", "bar", Symbol("baz"), "non-enum", "not-found"];
-  },
-  getOwnPropertyDescriptor: function(target, name) {
-    if (name == "non-enum") return {configurable: true};
-    if (name == "not-found") return undefined;
-    return {enumerable: true, configurable: true};
-  }
-}
-
-var proxy = new Proxy(target, handler);
-
-// Object.keys() ignores symbols and non-enumerable keys.
-assertEquals(["foo", "bar"], Object.keys(proxy));
-
-// Edge case: no properties left after filtering.
-handler.getOwnPropertyDescriptor = undefined;
-assertEquals([], Object.keys(proxy));
-
-// Throwing shouldn't crash.
-handler.getOwnPropertyDescriptor = function() { throw new Number(1); };
-assertThrows("Object.keys(proxy)", Number);
-
-// Fall through to target if there is no trap.
-handler.ownKeys = undefined;
-assertEquals(["target"], Object.keys(proxy));
-assertEquals(["target"], Object.keys(target));