diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/getprop-idempotent-cache-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/getprop-idempotent-cache-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,17 @@
+function f(o) {
+    var res = 0;
+    for (var i=0; i<11000; i++) {
+        res += o.x;
+    }
+    return res;
+}
+
+function O(x) {
+    if (x)
+        this.x = 10;
+}
+
+f(new O(true));
+
+// "o.x" is now missing so the idempotent cache should invalidate f.
+f(new O(false));