diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug744287.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug744287.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,6 @@
+function callbackfn(v) {
+  gczeal(4);
+  return arr[0] + (Uint8ClampedArray);
+}
+arr = [1,2,3,4,5];
+arr = arr.map(callbackfn);