[runtime] [proxy] implementing [[Get]] trap.

test/mjsunit/harmony/proxy/proxy-getPrototypeOf.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__ = {};
-var handler = { handler: 1 };
-var proxy = new Proxy(target, handler);
-
-assertSame(Object.getPrototypeOf(proxy), target.__proto__ );
-
-target.__proto__ = [];
-assertSame(Object.getPrototypeOf(proxy), target.__proto__);
-
-handler.getPrototypeOf = function() {
-  return 1;
-}
-assertThrows(function() { Object.getPrototypeOf(proxy) }, TypeError);
-
-var target_prototype = {a:1, b:2};
-handler.getPrototypeOf = function() {
-  return target_prototype ;
-}
-assertSame(Object.getPrototypeOf(proxy), target_prototype);
-
-// Test with proxy target:
-var proxy2 = new Proxy(proxy, {});
-assertSame(Object.getPrototypeOf(proxy2), target_prototype);
-
-// Test with Proxy handler:
-// TODO(neis,cbruni): Uncomment once the get trap works again.
-// var proxy3_prototype = {};
-// var handler_proxy = new Proxy({
-//   getPrototypeOf: function() { return proxy3_prototype }
-// }, {});
-// var proxy3 = new Proxy(target, handler_proxy);
-// assertSame(Object.getPrototypeOf(proxy3), target_prototype);