[geary/wip/765516-gtk-widget-conversation-viewer: 103/107] Mark ConversationMessage.context_menu_element as nullable.

[Michael Gratton <mjog src gnome org>]

commit 4dddb975ed6e2e12cb1cdf1ce7e9fe074f2c7583
Author: Michael James Gratton <mike vee net>
Date:   Fri May 13 11:49:22 2016 +1000

    Mark ConversationMessage.context_menu_element as nullable.

 .../conversation-viewer/conversation-message.vala  |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/client/conversation-viewer/conversation-message.vala 
b/src/client/conversation-viewer/conversation-message.vala
index e9126a3..7849cf3 100644
--- a/src/client/conversation-viewer/conversation-message.vala
+++ b/src/client/conversation-viewer/conversation-message.vala
@@ -126,7 +126,7 @@ public class ConversationMessage : Gtk.Box {
     private MenuModel? context_menu_inspector = null;
 
     // Last known DOM element under the context menu
-    private WebKit.DOM.HTMLElement context_menu_element;
+    private WebKit.DOM.HTMLElement? context_menu_element = null;
 
     // Contains the current mouse-over'ed link URL, if any
     private string? hover_url = null;