diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/arrays/length-set-after-has-sparse.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/arrays/length-set-after-has-sparse.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+var arr = [];
+Object.defineProperty(arr, 4, {
+  configurable: true,
+  enumerable: false,
+  writable: false,
+  value: undefined
+});
+for (var y = 0; y < 2; y++)
+  arr.length = 0;