diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testDecElem1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testDecElem1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,7 @@
+var obj = {p: 100};
+var name = "p";
+var a = [];
+for (var i = 0; i < 10; i++)
+    a[i] = --obj[name];
+assertEq(a.join(','), '99,98,97,96,95,94,93,92,91,90');
+assertEq(obj.p, 90);