[evolution] Avoid crash when moving away from a meeting invitation email

[Milan Crha <mcrha src gnome org>]

commit b0ebeeb1895fb6b85a9cd02ec2008f44e5e86f5e
Author: Milan Crha <mcrha redhat com>
Date:   Wed Mar 11 09:09:21 2015 +0100

    Avoid crash when moving away from a meeting invitation email
    
    Reported at https://bugzilla.redhat.com/show_bug.cgi?id=1200377

 modules/itip-formatter/itip-view.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/modules/itip-formatter/itip-view.c b/modules/itip-formatter/itip-view.c
index 92e6ca5..a434e16 100644
--- a/modules/itip-formatter/itip-view.c
+++ b/modules/itip-formatter/itip-view.c
@@ -1660,7 +1660,7 @@ itip_view_create_dom_bindings (ItipView *view,
        WebKitDOMDocument *doc;
 
        doc = webkit_dom_node_get_owner_document (WEBKIT_DOM_NODE (element));
-       view->priv->dom_document = doc;
+       view->priv->dom_document = g_object_ref (doc);
 
        el = webkit_dom_document_get_element_by_id (doc, CHECKBOX_RECUR);
        if (el) {