Align __lookupGetter__/__lookupSetter__ behavior with the spec

test/mjsunit/es6/promise-lookup-getter-setter.js

+// Copyright 2016 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.
+
+let get = () => {};
+let set = () => {};
+let target = {};
+let handler = {
+  getOwnPropertyDescriptor(target, prop) {
+    let configurable = true;
+    if (prop == "both") {
+      return { get, set, configurable };
+    } else if (prop == "get") {
+      return { get, configurable };
+    } else if (prop == "set") {
+      return { set, configurable };
+    } else if (prop == "data") {
+      return { value: 42, configurable };
+    } else {
+      return Reflect.getOwnPropertyDescriptor(target, prop);
+    }
+  }
+};
+
+// Test behavior on own properties.
+let proxy = new Proxy(target, handler);
+assertSame(get, proxy.__lookupGetter__("both"));
+assertSame(get, proxy.__lookupGetter__("get"));
+assertSame(undefined, proxy.__lookupGetter__("set"));
+assertSame(undefined, proxy.__lookupGetter__("data"));
+assertSame(set, proxy.__lookupSetter__("both"));
+assertSame(undefined, proxy.__lookupSetter__("get"));
+assertSame(set, proxy.__lookupSetter__("set"));
+assertSame(undefined, proxy.__lookupSetter__("data"));
+
+// Test behavior on the prototype chain.
+let object = { __proto__: proxy };
+assertSame(get, object.__lookupGetter__("both"));
+assertSame(get, object.__lookupGetter__("get"));
+assertSame(undefined, object.__lookupGetter__("set"));
+assertSame(undefined, object.__lookupGetter__("data"));
+assertSame(set, object.__lookupSetter__("both"));
+assertSame(undefined, object.__lookupSetter__("get"));
+assertSame(set, object.__lookupSetter__("set"));
+assertSame(undefined, object.__lookupSetter__("data"));
+
+// Test being shadowed while on prototype chain.
+let shadower = { __proto__: proxy, both: 1, get: 2, set: 3, data: 4 };
+assertSame(undefined, shadower.__lookupGetter__("both"));
+assertSame(undefined, shadower.__lookupGetter__("get"));
+assertSame(undefined, shadower.__lookupGetter__("set"));
+assertSame(undefined, shadower.__lookupGetter__("data"));
+assertSame(undefined, shadower.__lookupSetter__("both"));
+assertSame(undefined, shadower.__lookupSetter__("get"));
+assertSame(undefined, shadower.__lookupSetter__("set"));
+assertSame(undefined, shadower.__lookupSetter__("data"));
+
+// Test getPrototypeOf trap.
+let getFoo = () => {};
+let setFoo = () => {};
+let proto = {};
+Reflect.defineProperty(proto, "foo", { get: getFoo, set: setFoo });
+Reflect.setPrototypeOf(target, proto);
+assertSame(getFoo, proxy.__lookupGetter__("foo"));
+assertSame(setFoo, proxy.__lookupSetter__("foo"));
+handler.getPrototypeOf = () => null;
+assertSame(undefined, proxy.__lookupGetter__("foo"));
+assertSame(undefined, proxy.__lookupSetter__("foo"));
+handler.getPrototypeOf = () => proto;
+assertSame(getFoo, proxy.__lookupGetter__("foo"));
+assertSame(setFoo, proxy.__lookupSetter__("foo"));
+
+// Test shadowing the prototype.
+Reflect.defineProperty(proto, "data", { get: getFoo, set: setFoo });
+assertSame(undefined, proxy.__lookupGetter__("data"));
+assertSame(undefined, proxy.__lookupSetter__("data"));