diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testArrayInWithIndexedProto.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testArrayInWithIndexedProto.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,24 @@
+function testArrayInWithIndexedProto()
+{
+    Array.prototype[0] = "Got me";
+    var zeroPresent, zeroPresent2;
+    // Need to go to 18 because in the failure mode this is
+    // testing we have various side-exits in there due to interp and
+    // tracer not agreeing that confuse the issue and cause us to not
+    // hit the bad case within 9 iterations.
+    for (var j = 0; j < 18; ++j) {
+	zeroPresent = 0 in [];
+    }
+
+    var arr = [1, 2];
+    delete arr[0];
+    for (var j = 0; j < 18; ++j) {
+	zeroPresent2 = 0 in arr;
+    }
+    return [zeroPresent, zeroPresent2];
+}
+
+var [ret, ret2] = testArrayInWithIndexedProto();
+assertEq(ret, true);
+assertEq(ret2, true);
+