Add a way to add aliases for css properties

This will be used to rename some properties in a more
systematic way without breaking all users of the old name.

gtk/gtkstyleproperty.c

@@ -233,6 +233,26 @@ _gtk_style_property_init_properties (void)
   _gtk_css_shorthand_property_init_properties ();
 }
 
+void
+_gtk_style_property_add_alias (const gchar *name,
+                               const gchar *alias)
+{
+  GtkStylePropertyClass *klass;
+  GtkStyleProperty *property;
+
+  g_return_if_fail (name != NULL);
+  g_return_if_fail (alias != NULL);
+
+  klass = g_type_class_peek (GTK_TYPE_STYLE_PROPERTY);
+
+  property = g_hash_table_lookup (klass->properties, name);
+
+  g_assert (property != NULL);
+  g_assert (g_hash_table_lookup (klass->properties, alias) == NULL);
+
+  g_hash_table_insert (klass->properties, (gpointer)alias, property);
+}
+
 /**
  * _gtk_style_property_lookup:
  * @name: name of the property to lookup

gtk/gtkstylepropertyprivate.h

@@ -67,6 +67,9 @@ GType               _gtk_style_property_get_type             (void) G_GNUC_CONST
 
 void                _gtk_style_property_init_properties      (void);
 
+void                _gtk_style_property_add_alias (const gchar *name,
+                                                   const gchar *alias);
+
 GtkStyleProperty *       _gtk_style_property_lookup        (const char             *name);
 
 const char *             _gtk_style_property_get_name      (GtkStyleProperty       *property);