Array.prototype.{reduce, reduceRight}: Wrong order of operations when determining initial value.

test/mjsunit/array-reduce.js

 // Copyright 2009 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 503 matching lines @@
   return a + b;
 }
 
 var arr = [1, 2, 3, 4];
 testReduce("reduce", "ArrayManipulationExtender", 10,
            [[0, 1, 0, [1, 2, 3, 4], 1],
             [1, 2, 1, [1, 2, 3, 4, 4], 3],
             [3, 3, 2, [1, 2, 3, 4, 4, 5], 6],
             [6, 4, 3, [1, 2, 3, 4, 4, 5, 6], 10],
            ], arr, extender, 0);
+
+var a = [];
+Object.defineProperty(a, "0", { get: function() { delete this[0] },
+  configurable: true });
+var result = a.reduce(function(a) { return a });
+assertTrue(result === undefined);
+
+var a = [];
+Object.defineProperty(a, "0", {get: function() { delete this[0] },

[wingo, 2014/10/07 11:04:31]

Inconsistent spacing here (before the get), and i find the two-line break for
this descriptor a bit wonky; maybe that's just me.

The test is better as:
assertEquals(undefined, a.reduce(function (a) { return a }))

+  configurable: true});
+var result = a.reduceRight(function(a) { return a });
+assertTrue(result === undefined);