[FIX] mail: chatter not shown when should

If the chatter is displayed, display the send message part.

Before it was only displayed if we can edit the record, but we are still
able to post in other case (i.e. if we are in the followers).

closes #6721
opw-631039

addons/mail/static/src/js/mail.js

@@ -1816,10 +1816,9 @@ openerp.mail = function (session) {
                 this.$('oe_mail_thread').hide();
                 return;
             }
-
             this.node.params = _.extend(this.node.params, {
                 'message_ids': this.get_value(),
-                'show_compose_message': this.view.is_action_enabled('edit'),
+                'show_compose_message': true,
             });
             this.node.context = {
                 'mail_read_set_read': true,  // set messages as read in Chatter