[gtk] color plane: Don't allocate 0-size textures

[Matthias Clasen <matthiasc src gnome org>]

commit 4df64bce834530ba51f72f5a35896e36657e2309
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 20 12:49:56 2019 +0000

    color plane: Don't allocate 0-size textures
    
    This triggers critials, and does us no good.

 gtk/gtkcolorplane.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/gtk/gtkcolorplane.c b/gtk/gtkcolorplane.c
index 17f658c9ac..8cf817eb1a 100644
--- a/gtk/gtkcolorplane.c
+++ b/gtk/gtkcolorplane.c
@@ -129,6 +129,9 @@ create_texture (GtkColorPlane *plane)
   width = gtk_widget_get_width (widget);
   height = gtk_widget_get_height (widget);
 
+  if (width == 0 || height == 0)
+    return;
+
   g_clear_object (&plane->priv->texture);
 
   stride = width * 4;