diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug831087.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug831087.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,15 @@
+function isNegZero(x) {
+  return x===0 && (1/x)===-Infinity;
+}
+
+try {
+    for (y = 0; y < 1; y++) {
+        x = y;
+    }
+} catch (e) {}
+
+function f() {
+    (x /= -9)
+}
+f()
+assertEq(isNegZero(this.x), true);