[builtins] Also simplify the Symbol constructor.

src/symbol.js

 // Copyright 2013 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) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var GlobalObject = global.Object;
 var GlobalSymbol = global.Symbol;
 var hasInstanceSymbol = utils.ImportNow("has_instance_symbol");
 var isConcatSpreadableSymbol =
     utils.ImportNow("is_concat_spreadable_symbol");
 var isRegExpSymbol = utils.ImportNow("is_regexp_symbol");
 var iteratorSymbol = utils.ImportNow("iterator_symbol");
 var ObjectGetOwnPropertyKeys;
 var toPrimitiveSymbol = utils.ImportNow("to_primitive_symbol");
-var ToString;
 var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 var unscopablesSymbol = utils.ImportNow("unscopables_symbol");
 
 utils.Import(function(from) {
   ObjectGetOwnPropertyKeys = from.ObjectGetOwnPropertyKeys;
-  ToString = from.ToString;
 });
 
 // -------------------------------------------------------------------
 
-function SymbolConstructor(x) {
-  if (%_IsConstructCall()) throw MakeTypeError(kNotConstructor, "Symbol");
-  // NOTE: Passing in a Symbol value will throw on ToString().
-  return %CreateSymbol(IS_UNDEFINED(x) ? x : ToString(x));
-}
-
-
 // 19.4.3.4 Symbol.prototype [ @@toPrimitive ] ( hint )
 function SymbolToPrimitive(hint) {
   if (!(IS_SYMBOL(this) || IS_SYMBOL_WRAPPER(this))) {
     throw MakeTypeError(kIncompatibleMethodReceiver,
                         "Symbol.prototype [ @@toPrimitive ]", this);
   }
   return %_ValueOf(this);
 }
 
 
@@ skipping 37 matching lines @@
 function ObjectGetOwnPropertySymbols(obj) {
   obj = TO_OBJECT(obj);
 
   // TODO(arv): Proxies use a shared trap for String and Symbol keys.
 
   return ObjectGetOwnPropertyKeys(obj, PROPERTY_ATTRIBUTES_STRING);
 }
 
 // -------------------------------------------------------------------
 
-%SetCode(GlobalSymbol, SymbolConstructor);
 %FunctionSetPrototype(GlobalSymbol, new GlobalObject());
 
 utils.InstallConstants(GlobalSymbol, [
   // TODO(rossberg): expose when implemented.
   // "hasInstance", hasInstanceSymbol,
   // "isConcatSpreadable", isConcatSpreadableSymbol,
   // "isRegExp", isRegExpSymbol,
   "iterator", iteratorSymbol,
   "toPrimitive", toPrimitiveSymbol,
   // TODO(dslomov, caitp): Currently defined in harmony-tostring.js ---
@@ skipping 26 matching lines @@
 ]);
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.SymbolToString = SymbolToString;
 })
 
 })