diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug517721.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug517721.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,8 @@
+try {
+    for (var j = 0; j < 2; ++j) {
+        if (j == 1) {
+            ++(null[2]);
+        }
+    }
+} catch(e) {
+}