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

test/mjsunit/array-reduce.js

Index: test/mjsunit/array-reduce.js
diff --git a/test/mjsunit/array-reduce.js b/test/mjsunit/array-reduce.js
index 429f34808d74152e25705b296dc584c2f41837e0..3b243145027da05c13a16e85f2d2f7a29e6945a3 100644
--- a/test/mjsunit/array-reduce.js
+++ b/test/mjsunit/array-reduce.js
@@ -521,3 +521,15 @@ testReduce("reduce", "ArrayManipulationExtender", 10,
             [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);