button: Remove nullable annotation for new_from_icon_name()

This makes it more consistent with set_icon_name() which
does also not accept NULL.

Fixes #5606

diff --git a/gtk/gtkbutton.c b/gtk/gtkbutton.c
index dda8c194ee129109e0aee4be39adc8136ec03545..a5b004488540d9ad0df03214a9487ee8b393de7c 100644 (file)
--- a/gtk/gtkbutton.c
+++ b/gtk/gtkbutton.c
@@ -638,7 +638,7 @@ gtk_button_new_with_label (const char *label)
 
 /**
  * gtk_button_new_from_icon_name:
- * @icon_name: (nullable): an icon name
+ * @icon_name: an icon name
  *
  * Creates a new button containing an icon from the current icon theme.
  *