[gxml] GXmlHashMapAttr: remove property using libxml2

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 0f99d5e2fde7a4d393e37c1e30b16d9e719a6035
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Mar 1 11:39:10 2017 -0600

    GXmlHashMapAttr: remove property using libxml2
    
    This removes a warning.

 gxml/GXmlHashMapAttr.vala |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/gxml/GXmlHashMapAttr.vala b/gxml/GXmlHashMapAttr.vala
index 2b5fde2..309271c 100644
--- a/gxml/GXmlHashMapAttr.vala
+++ b/gxml/GXmlHashMapAttr.vala
@@ -318,7 +318,9 @@ public class GXml.GHashMapAttr : Gee.AbstractMap<string,GXml.Node>,
       throw new GXml.DomError.NO_MODIFICATION_ALLOWED_ERROR (_("Node collection is read only"));
     // FIXME: Detects if no namespace is supported to rise exception  NOT_SUPPORTED_ERROR
     if (_parent is DomElement) {
-      (_parent as DomElement).set_attribute_ns (namespace_uri, local_name, null);
+      var ns = (_parent as GNode).get_internal_node ()->doc->search_ns_by_href ((_parent as 
GNode).get_internal_node (),
+                                                              namespace_uri);
+      (_parent as GNode).get_internal_node ()->set_ns_prop (ns, local_name, null);
       return n;
     }
     return null;