Add a --harmony-species flag, defining @@species on constructors

src/js/harmony-species.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.
+
+(function(global, utils, extrasUtils) {
+
+"use strict";
+
+%CheckIsBootstrapping();
+
+var GlobalArray = global.Array;
+// It is important that this file is run after src/js/typedarray.js,
+// otherwise GlobalTypedArray would be Object, and we would break
+// old versions of Zepto.
+var GlobalTypedArray = global.Uint8Array.__proto__;
+var GlobalMap = global.Map;
+var GlobalSet = global.Set;
+var GlobalArrayBuffer = global.ArrayBuffer;
+var GlobalPromise = global.Promise;
+var GlobalRegExp = global.RegExp;
+var speciesSymbol = utils.ImportNow("species_symbol");
+
+function ArraySpecies() {
+  return this;
+}
+
+function TypedArraySpecies() {
+  return this;
+}
+
+function MapSpecies() {
+  return this;
+}
+
+function SetSpecies() {
+  return this;
+}
+
+function ArrayBufferSpecies() {
+  return this;
+}
+
+function PromiseSpecies() {
+  return this;
+}
+
+function RegExpSpecies() {
+  return this;
+}
+
+utils.InstallGetter(GlobalArray, speciesSymbol, ArraySpecies, DONT_ENUM);
+utils.InstallGetter(GlobalTypedArray, speciesSymbol, TypedArraySpecies, DONT_ENUM);
+utils.InstallGetter(GlobalMap, speciesSymbol, MapSpecies, DONT_ENUM);
+utils.InstallGetter(GlobalSet, speciesSymbol, SetSpecies, DONT_ENUM);
+utils.InstallGetter(GlobalArrayBuffer, speciesSymbol, ArrayBufferSpecies,
+                    DONT_ENUM);
+utils.InstallGetter(GlobalPromise, speciesSymbol, PromiseSpecies, DONT_ENUM);
+utils.InstallGetter(GlobalRegExp, speciesSymbol, RegExpSpecies, DONT_ENUM);
+
+});