[es6] support `get` and `set` in shorthand properties

test/mjsunit/es6/object-literals-property-shorthand.js

 // Copyright 2014 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 TestBasics() {
   var x = 1;
   var object = {x};
   assertEquals(1, object.x);
 })();
 
 
+(function TestBasicsGetSet() {
+  var get = 1, set = 2;
+  var object = {get, set};
+  assertEquals(1, object.get);
+  assertEquals(2, object.set);
+})();
+
+
 (function TestDescriptor() {
   var x = 1;
   var object = {x};
   var descr = Object.getOwnPropertyDescriptor(object, 'x');
   assertEquals(1, descr.value);
   assertTrue(descr.enumerable);
   assertTrue(descr.writable);
   assertTrue(descr.configurable);
 })();
 
@@ skipping 39 matching lines @@
 (function TestProtoName2() {
   var __proto__ = 1;
   var p = {};
   var object = {
     __proto__: p,
     __proto__,
   };
   assertEquals(p, Object.getPrototypeOf(object));
   assertEquals(1, object.__proto__);
 })();