diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/getelem-proto.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/getelem-proto.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+var a = [1, , 2];
+Array.prototype[1] = 3;
+
+function f(arr) {
+    return arr[0] + arr[1] + arr[2];
+}
+for (var i=0; i<70; i++) {
+    assertEq(f(a), 6);
+}
+
+Object.defineProperty(Array.prototype, "1", {
+    get: function() {
+        return 1234;
+    }
+});
+
+assertEq(f(a), 1237);
+assertEq(f(a), 1237);