[gtk] button: Remove some dead code

[Timm Bäder <baedert src gnome org>]

commit 2644da106b8f198ed7eae6ac5bd4c4ee81694223
Author: Timm Bäder <mail baedert org>
Date:   Mon Dec 3 19:07:54 2018 +0100

    button: Remove some dead code

 gtk/gtkbutton.c | 6 ------
 1 file changed, 6 deletions(-)
---
diff --git a/gtk/gtkbutton.c b/gtk/gtkbutton.c
index 0534814df7..9dae0101cc 100644
--- a/gtk/gtkbutton.c
+++ b/gtk/gtkbutton.c
@@ -799,12 +799,6 @@ gtk_real_button_activate (GtkButton *button)
 {
   GtkWidget *widget = GTK_WIDGET (button);
   GtkButtonPrivate *priv = gtk_button_get_instance_private (button);
-  GdkDevice *device;
-
-  device = gtk_get_current_event_device ();
-
-  if (device && gdk_device_get_source (device) != GDK_SOURCE_KEYBOARD)
-    device = gdk_device_get_associated_device (device);
 
   if (gtk_widget_get_realized (widget) && !priv->activate_timeout)
     {