diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug858586.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug858586.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+function A(a) { this.a = a; }
+A.prototype.foo = function (x) {};
+function B(b) { this.b = b; }
+B.prototype.foo = function (x) {};
+function C(c) {}
+function makeArray(n) {
+    var classes = [A, B, C];
+    var arr = [];
+    for (var i = 0; i < n; i++) {
+        arr.push(new classes[i % 3](i % 3));
+    }
+    return arr;
+}
+function runner(arr, resultArray, len) {
+    for (var i = 0; i < len; i++) {
+        var obj = arr[i];
+        resultArray[0] += obj.foo(i);
+    }
+}
+var resultArray = [0];
+var arr = makeArray(30000);
+C.prototype.foo = Uint8ClampedArray;
+runner(arr, resultArray, 30000);