Fix for bug 617247 (Don't call HoldScriptObject if we don't have a script object). r=sicking.

--HG--
extra : rebase_source : cba480742dc8a2fe356b6b65c10ea1e0b6023730

content/xul/content/src/nsXULElement.h

@@ -359,6 +359,8 @@ public:
     {
         NS_ASSERTION(!mScriptObject.mObject, "Leaking script object.");
         if (!aObject) {
+            mScriptObject.mObject = nsnull;
+
             return;
         }