Followup to bug 538918 - Don't leak gNeuteredWindows, r=jimm

--HG--
extra : transplant_source : %1D%9C%3Eg%A2%ACV%3DY%F3%92%C8b%BDxB%3A.e%A7

ipc/glue/WindowsMessageLoop.cpp

@@ -501,6 +501,8 @@ UnhookNeuteredWindows()
     RestoreWindowProcedure(gNeuteredWindows->ElementAt(index));
   }
   gNeuteredWindows->Clear();
+  delete gNeuteredWindows;
+  gNeuteredWindows = NULL;
 }
 
 void