[gtk+] Add -gtk-image-effect alias for -gtk-icon-effect

[Christoph Reiter <creiter src gnome org>]

commit 3a15aa2a957b7a4fc5ecdb21d800b2e81bb2ea47
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Tue Feb 16 15:49:23 2016 +0100

    Add -gtk-image-effect alias for -gtk-icon-effect
    
    The property name was changed in 2396265523dfc6. This makes sure
    apps using it don't break and get a helpful warning instead.

 gtk/gtkcssstylepropertyimpl.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkcssstylepropertyimpl.c b/gtk/gtkcssstylepropertyimpl.c
index cee8e27..c344d3f 100644
--- a/gtk/gtkcssstylepropertyimpl.c
+++ b/gtk/gtkcssstylepropertyimpl.c
@@ -1785,6 +1785,7 @@ _gtk_css_style_property_init_properties (void)
                                          NULL,
                                          NULL,
                                          _gtk_css_icon_effect_value_new (GTK_CSS_ICON_EFFECT_NONE));
+  _gtk_style_property_add_alias ("-gtk-icon-effect", "-gtk-image-effect");
 
 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
   gtk_css_style_property_register        ("engine",