[gtkmm] ComboBox: Remove some now-unnecessary code.

[Murray Cumming <murrayc src gnome org>]

commit 9a947442cd8d70701843fe8c54f9f32757f0b319
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Oct 9 10:34:41 2013 +0200

    ComboBox: Remove some now-unnecessary code.

 gtk/src/comboboxtext.ccg |    7 +------
 1 files changed, 1 insertions(+), 6 deletions(-)
---
diff --git a/gtk/src/comboboxtext.ccg b/gtk/src/comboboxtext.ccg
index f0a64a5..206f448 100644
--- a/gtk/src/comboboxtext.ccg
+++ b/gtk/src/comboboxtext.ccg
@@ -23,13 +23,8 @@ namespace Gtk
 
 ComboBoxText::ComboBoxText(bool has_entry)
 :
-  //TODO The settings of entry-text-column and id-column can be removed,
-  //when old versions of GTK+ (before 2011-12-30) need not be supported.
-  //These properties are now set in gtk_combo_box_text_constructor().
-  //See bug 612396 (gtk+) and 653579 (gtkmm).
-
   //The entry-text-column and id-column values are copied from gtk_combo_box_text_new():
-  _CONSTRUCT("has-entry", gboolean(has_entry), "entry-text-column", 0, "id-column", 1)
+  _CONSTRUCT("has-entry", gboolean(has_entry))
 {}
 
 void ComboBoxText::set_active_text(const Glib::ustring& text)