[proxies] [[HasProperty]]: fix trap call.

src/js/proxy.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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 112 matching lines @@
     }
   }
   this.defineProperty(name, {
     value: val,
     writable: true,
     enumerable: true,
     configurable: true});
   return true;
 }
 
-function DerivedHasTrap(name) {
-  return !!this.getPropertyDescriptor(name)
-}
-
 function DerivedHasOwnTrap(name) {
   return !!this.getOwnPropertyDescriptor(name)
 }
 
 function DerivedKeysTrap() {
   var names = this.getOwnPropertyNames()
   var enumerableNames = []
   for (var i = 0, count = 0; i < names.length; ++i) {
     var name = names[i]
     if (IS_SYMBOL(name)) continue
@@ skipping 43 matching lines @@
 // Exports
 
 utils.Export(function(to) {
   to.ProxyDelegateCallAndConstruct = DelegateCallAndConstruct;
   to.ProxyDerivedHasOwnTrap = DerivedHasOwnTrap;
   to.ProxyDerivedKeysTrap = DerivedKeysTrap;
 });
 
 %InstallToContext([
   "derived_get_trap", DerivedGetTrap,
-  "derived_has_trap", DerivedHasTrap,
   "derived_set_trap", DerivedSetTrap,
   "proxy_enumerate", ProxyEnumerate,
 ]);
 
 })