[gtk+] Drop the icon-shadow property name

[Matthias Clasen <matthiasc src gnome org>]

commit 226aee08286b7e1d2f024f55d8017a62c541ea6f
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Sep 17 16:51:05 2017 -0400

    Drop the icon-shadow property name
    
    This has been deprecated for a while. Just use the -gtk-prefixed
    name.

 gtk/gtkcssstylepropertyimpl.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkcssstylepropertyimpl.c b/gtk/gtkcssstylepropertyimpl.c
index 3a3db71..fc4156d 100644
--- a/gtk/gtkcssstylepropertyimpl.c
+++ b/gtk/gtkcssstylepropertyimpl.c
@@ -1424,7 +1424,6 @@ _gtk_css_style_property_init_properties (void)
                                           shadow_value_parse,
                                           NULL,
                                           _gtk_css_shadows_value_new_none ());
-  _gtk_style_property_add_alias ("-gtk-icon-shadow", "icon-shadow");
   gtk_css_style_property_register        ("-gtk-icon-style",
                                           GTK_CSS_PROPERTY_ICON_STYLE,
                                           G_TYPE_NONE,