[builtins] Fix ToString in Array.prototype.join.

src/runtime.js

 // Copyright 2006-2008 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.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
 
 // The following declarations are shared with other native JS files.
 // They are all declared at this one spot to avoid redeclaration errors.
-var $defaultString;
 var $NaN;
 var $nonNumberToNumber;
 var $sameValue;
 var $sameValueZero;
 var $toInteger;
 var $toLength;
 var $toNumber;
 var $toPositiveInteger;
 
 var harmony_tolength = false;
@@ skipping 313 matching lines @@
 // NOTE: Setting the prototype for Array must take place as early as
 // possible due to code generation for array literals.  When
 // generating code for a array literal a boilerplate array is created
 // that is cloned when running the code.  It is essential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype(GlobalArray, new GlobalArray(0));
 
 // ----------------------------------------------------------------------------
 // Exports
 
-$defaultString = DefaultString;
 $NaN = %GetRootNaN();
 $nonNumberToNumber = NonNumberToNumber;
 $sameValue = SameValue;
 $sameValueZero = SameValueZero;
 $toInteger = ToInteger;
 $toLength = ToLength;
 $toNumber = ToNumber;
 $toPositiveInteger = ToPositiveInteger;
 
 %InstallToContext([
@@ skipping 12 matching lines @@
 ]);
 
 utils.Export(function(to) {
   to.ToBoolean = ToBoolean;
   to.ToLength = ToLength;
   to.ToNumber = ToNumber;
   to.ToString = ToString;
 });
 
 })