[vala/0.48] gtk4: Update to 3.99.3+8880e3bd

[Rico Tzschichholz <ricotz src gnome org>]

commit 295f4c963fc2f321a43ffc63f1daefbafa7ffb0f
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Wed Oct 21 16:49:38 2020 +0200

    gtk4: Update to 3.99.3+8880e3bd
    
    Fixes https://gitlab.gnome.org/GNOME/vala/issues/1089

 vapi/gtk4.vapi | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/vapi/gtk4.vapi b/vapi/gtk4.vapi
index 7dfae7f9e..0b985e7e6 100644
--- a/vapi/gtk4.vapi
+++ b/vapi/gtk4.vapi
@@ -12022,11 +12022,11 @@ namespace Gtk {
                public bool activate_action_variant (string name, GLib.Variant? args);
                public void activate_default ();
                [CCode (cname = "gtk_widget_class_add_binding")]
-               public class void add_binding (uint keyval, Gdk.ModifierType mods, Gtk.ShortcutFunc callback, 
string format_string, ...);
+               public class void add_binding (uint keyval, Gdk.ModifierType mods, Gtk.ShortcutFunc callback, 
string? format_string, ...);
                [CCode (cname = "gtk_widget_class_add_binding_action")]
-               public class void add_binding_action (uint keyval, Gdk.ModifierType mods, string action_name, 
string format_string, ...);
+               public class void add_binding_action (uint keyval, Gdk.ModifierType mods, string action_name, 
string? format_string, ...);
                [CCode (cname = "gtk_widget_class_add_binding_signal")]
-               public class void add_binding_signal (uint keyval, Gdk.ModifierType mods, string @signal, 
string format_string, ...);
+               public class void add_binding_signal (uint keyval, Gdk.ModifierType mods, string @signal, 
string? format_string, ...);
                public void add_controller (owned Gtk.EventController controller);
                public void add_css_class (string css_class);
                public void add_mnemonic_label (Gtk.Widget label);
@@ -12530,6 +12530,7 @@ namespace Gtk {
                public void finish_delegate ();
                public float get_alignment ();
                public string get_chars (int start_pos = 0, int end_pos = -1);
+               public abstract unowned Gtk.Editable? get_delegate ();
                public bool get_editable ();
                public bool get_enable_undo ();
                public int get_max_width_chars ();