diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/for-of/array-holes-3.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/for-of/array-holes-3.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,8 @@
+// for-of consults Array.prototype when it encounters a hole.
+
+Array.prototype[1] = 'peek';
+var log = [];
+for (var x of [0, , 2, 3])
+    log.push(x);
+assertEq(log[1], 'peek');
+assertEq(log.join(), "0,peek,2,3");