[runtime] [proxy] implement [[Construct]]

test/mjsunit/es6/classes-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.
 
 // Flags: --allow-natives-syntax --harmony-proxies --harmony-reflect
 
 function CreateConstructableProxy(handler) {
-  return Proxy.createFunction(handler, function() {}, function() {});
+  return new Proxy(function(){}, handler);
 }
 
 (function() {
   var prototype = { x: 1 };
   var log = [];
 
   var proxy = CreateConstructableProxy({
     get(k) {
       log.push("get trap");
       return prototype;
@@ skipping 45 matching lines @@
     get(k) {
       log.push("get trap");
       return prototype;
     }});
 
   var o = Reflect.construct(Array, [1, 2, 3], proxy);
   assertEquals(["get trap"], log);
   assertTrue(Object.getPrototypeOf(o) === prototype);
   assertEquals([1, 2, 3], o);
 })();