[gtk] Drop GtkInvisible

[Matthias Clasen <matthiasc src gnome org>]

commit c35554cf6898b664adfd3e55047f497903adfd5f
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Feb 23 23:14:29 2019 -0500

    Drop GtkInvisible
    
    It was already private, and the previous commit removed
    the last use.

 gtk/gtkinvisible.c        | 295 ----------------------------------------------
 gtk/gtkinvisibleprivate.h |  80 -------------
 gtk/gtkwidget.c           |   1 -
 gtk/gtkwidgetprivate.h    |   1 -
 gtk/meson.build           |   1 -
 5 files changed, 378 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index a5f84c9137..f3dbb7316a 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -12075,7 +12075,6 @@ static gboolean
 gtk_widget_class_get_visible_by_default (GtkWidgetClass *widget_class)
 {
   return !(GTK_IS_WINDOW_CLASS (widget_class) ||
-           GTK_IS_INVISIBLE_CLASS (widget_class) ||
            GTK_IS_POPOVER_CLASS (widget_class));
 }
 
diff --git a/gtk/gtkwidgetprivate.h b/gtk/gtkwidgetprivate.h
index d0f3016364..49c4d19de0 100644
--- a/gtk/gtkwidgetprivate.h
+++ b/gtk/gtkwidgetprivate.h
@@ -35,7 +35,6 @@
 #include "gtkrootprivate.h"
 #include "gtksizerequestcacheprivate.h"
 #include "gtkwindowprivate.h"
-#include "gtkinvisibleprivate.h"
 #include "gtkgesture.h"
 
 #include "gsk/gskrendernodeprivate.h"
diff --git a/gtk/meson.build b/gtk/meson.build
index 33b723041b..2c705982a9 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -259,7 +259,6 @@ gtk_public_sources = files([
   'gtkimmodule.c',
   'gtkimmulticontext.c',
   'gtkinfobar.c',
-  'gtkinvisible.c',
   'gtklabel.c',
   'gtklayout.c',
   'gtklevelbar.c',