From cb3e0b1f2bd7ec74187e80f7faa2ba8e65249fb2 Mon Sep 17 00:00:00 2001
From: Chen Zeyu <zeyufly@gmail.com>
Date: Wed, 5 Dec 2012 14:13:26 -0800
Subject: [PATCH] Bug 813801: null-check blocklistWindow in
 nsBlocklistService.js. r=dtownsend

---
 toolkit/mozapps/extensions/nsBlocklistService.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/toolkit/mozapps/extensions/nsBlocklistService.js b/toolkit/mozapps/extensions/nsBlocklistService.js
index a33262bb4c5..85ed0450734 100644
--- a/toolkit/mozapps/extensions/nsBlocklistService.js
+++ b/toolkit/mozapps/extensions/nsBlocklistService.js
@@ -1038,7 +1038,8 @@ Blocklist.prototype = {
 
       let blocklistWindow = Services.ww.openWindow(null, URI_BLOCKLIST_DIALOG, "",
                               "chrome,centerscreen,dialog,titlebar", args);
-      blocklistWindow.addEventListener("unload", blocklistUnloadHandler, false);
+      if (blocklistWindow)
+        blocklistWindow.addEventListener("unload", blocklistUnloadHandler, false);
     });
   },