Removed check on element in case it is undefined in ArrayIndexOf - according ...

src/array.js

 // Copyright 2006-2008 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 965 matching lines @@
     var current = this[i];
     if (!IS_UNDEFINED(current) || i in this) {
       result[i] = f.call(receiver, current, i, this);
     }
   }
   return result;
 }
 
 
 function ArrayIndexOf(element, index) {
-  if (IS_UNDEFINED(element)) {
-    throw MakeTypeError('array_indexof_not_defined', [element]);
-  }
   var length = this.length;
   if (index == null) {
     index = 0;
   } else {
     index = TO_INTEGER(index);
     // If index is negative, index from the end of the array.
     if (index < 0) index = length + index;
     // If index is still negative, search the entire array.
     if (index < 0) index = 0;
   }
@@ skipping 149 matching lines @@
     ArrayIndexOf: 1,
     ArrayLastIndexOf: 1,
     ArrayPush: 1,
     ArrayReduce: 1,
     ArrayReduceRight: 1
   });
 }
 
 
 SetupArray();