diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug777992.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug777992.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+verifyprebarriers()
+x = []
+function z() {}
+Object.defineProperty(x, 2, {
+    value: z
+})
+gczeal(2, 2)
+y = x.slice(2)
+y.e = (function() {})