[gtk+] Fix a compiler warning

[Matthias Clasen <matthiasc src gnome org>]

commit 7aa236fbb2a342e2d91a2a1c8690d87c7cec512e
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Nov 8 22:09:34 2017 -0500

    Fix a compiler warning

 gtk/gtkcssimagerecolor.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkcssimagerecolor.c b/gtk/gtkcssimagerecolor.c
index 2aed610..48cae0d 100644
--- a/gtk/gtkcssimagerecolor.c
+++ b/gtk/gtkcssimagerecolor.c
@@ -183,7 +183,7 @@ gtk_css_image_recolor_load (GtkCssImageRecolor  *recolor,
 
   g_clear_error (&local_error);
 
-  return image;
+  return GTK_CSS_IMAGE (image);
 }
 
 static void