[gtk+] docs: Add missing Since tag

[Benjamin Otte <otte src gnome org>]

commit ae6ab3951c9ef08efe15e5be6c0ae44fff68e452
Author: Benjamin Otte <otte redhat com>
Date:   Fri Mar 16 02:19:15 2012 +0100

    docs: Add missing Since tag

 gtk/gtkstyleprovider.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkstyleprovider.c b/gtk/gtkstyleprovider.c
index b1c7d49..80f411c 100644
--- a/gtk/gtkstyleprovider.c
+++ b/gtk/gtkstyleprovider.c
@@ -93,6 +93,8 @@ gtk_style_provider_get_style (GtkStyleProvider *provider,
  * the widget represented by @path.
  *
  * Returns: %TRUE if the property was found and has a value, %FALSE otherwise
+ *
+ * Since: 3.0
  **/
 gboolean
 gtk_style_provider_get_style_property (GtkStyleProvider *provider,