[gxml] More prototypes for SerializableXOM

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit f4682b54c422667b3e53c36db89c8c428c3bb49f
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Feb 17 21:12:39 2016 -0600

    More prototypes for SerializableXOM

 gxml/SerializableXOM.vala |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/gxml/SerializableXOM.vala b/gxml/SerializableXOM.vala
index 2e98d61..6468e6f 100644
--- a/gxml/SerializableXOM.vala
+++ b/gxml/SerializableXOM.vala
@@ -247,7 +247,7 @@ public abstract class GXml.SerializableXOM : GXml.TwDocument, GXml.Serializable
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
-    return null;
+    return element;
   }
 
   public virtual GXml.Node? deserialize (GXml.Node node)
@@ -304,7 +304,6 @@ public abstract class GXml.SerializableXOM : GXml.TwDocument, GXml.Serializable
     }
     return false;
   }
-  public abstract string to_string ();
 
   public class ChildrenList : ArrayList<GXml.Node> {
     private SerializableXOM serializable;