[epiphany] notebook: add missing cast

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 219954d5b7adee344a488663824ed8f70e56409b
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Feb 11 12:19:23 2017 -0600

    notebook: add missing cast
    
    Oops!

 src/ephy-notebook.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/ephy-notebook.c b/src/ephy-notebook.c
index 1d527bb..7f514f0 100644
--- a/src/ephy-notebook.c
+++ b/src/ephy-notebook.c
@@ -580,7 +580,7 @@ ephy_notebook_rebuild_tab_menu (EphyNotebook *notebook)
     g_object_unref (item);
   }
 
-  current_page = gtk_notebook_get_current_page (notebook);
+  current_page = gtk_notebook_get_current_page (GTK_NOTEBOOK (notebook));
   if (current_page < 0)
     return;