[geary/wip/765516-gtk-widget-conversation-viewer: 134/142] Really(?) fix DOM node crit warning when ConversationMessage finalised.

[Michael Gratton <mjog src gnome org>]

commit b8865ed42e3b1cfcf0ee9b4f3fa823906641ad03
Author: Michael James Gratton <mike vee net>
Date:   Fri Aug 19 13:31:52 2016 +1000

    Really(?) fix DOM node crit warning when ConversationMessage finalised.

 .../conversation-viewer/conversation-message.vala  |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/src/client/conversation-viewer/conversation-message.vala 
b/src/client/conversation-viewer/conversation-message.vala
index e8283c5..b311d83 100644
--- a/src/client/conversation-viewer/conversation-message.vala
+++ b/src/client/conversation-viewer/conversation-message.vala
@@ -310,6 +310,11 @@ public class ConversationMessage : Gtk.Grid {
         this.body.pack_start(this.web_view, true, true, 0);
     }
 
+    public override void destroy() {
+        this.context_menu_element = null;
+        base.destroy();
+    }
+
     /**
      * Shows the complete message and hides the preview headers.
      */