diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug643249.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug643249.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+{
+    function x() {}
+}
+for (i = 0; i < 10; i++) {
+    _someglobal_ = /a/;
+    (function() {
+        return function() {
+            return _someglobal_
+        } ()
+    } () == /a/);
+    gc();
+    try { _someglobal_ = new Function.__lookupSetter__ } catch (e) {}
+}