ES6 symbols: Implement Symbol intrinsic and basic functionality

src/v8natives.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 213 matching lines @@
 
 %SetProperty($Boolean.prototype, "constructor", $Boolean, DONT_ENUM);
 
 // ----------------------------------------------------------------------------
 // Object
 
 $Object.prototype.constructor = $Object;
 
 // ECMA-262 - 15.2.4.2
 function ObjectToString() {
-  if (IS_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
-    return '[object Undefined]';
-  }
-  if (IS_NULL(this)) return '[object Null]';
+  if (IS_UNDEFINED(this) && !IS_UNDETECTABLE(this)) return "[object Undefined]";
+  if (IS_NULL(this)) return "[object Null]";
+  if (IS_SYMBOL(this)) return "[object Symbol]";
   return "[object " + %_ClassOf(ToObject(this)) + "]";
 }
 
 
 // ECMA-262 - 15.2.4.3
 function ObjectToLocaleString() {
   if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
     throw MakeTypeError("called_on_null_or_undefined",
                         ["Object.prototype.toLocaleString"]);
   }
@@ skipping 1470 matching lines @@
 
 function SetUpFunction() {
   %CheckIsBootstrapping();
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetUpFunction();