[runtime] support new Proxy() instead of Proxy.create and install getPrototypeOf 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.__proto__ = {};
+var handler = {};
+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);