diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/for-of/array-holes-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/for-of/array-holes-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,10 @@
+// for-of does not skip Array holes. The value at a hole is undefined.
+
+var a = [0, , 2, 3];
+var log = [];
+for (var x of a) {
+    assertEq(x, a[log.length]);
+    log.push(x);
+}
+assertEq(log[1], undefined);
+assertEq(log.join(), "0,,2,3");