Inbox counts: Remove live alter of unread count when mark-on-open is off

This is a good interaction in theory, but gets pretty hairy to test for
in practice due to modmail being a subset of messages as well as
subreddit messages not being restricted to modmail. This issue is
blocking release, so remove the buggy feature for rollout to be addressed
at a later date.

r2/r2/public/static/js/reddit.js

@@ -186,20 +186,12 @@ function change_state(elem, op, callback, keep, post_callback) {
     return false;
 };
 
-function alterUnreadCount(num) {
-  var msgCount = $('.message-count');
-  if (msgCount.length > 0) {
-    msgCount.text(parseInt(msgCount.text(), 10) + num);
-  }
-}
-
 function unread_thing(elem) {
     var t = $(elem);
     if (!t.hasClass("thing")) {
         t = t.thing();
     }
 
-    alterUnreadCount(1);
     $(t).addClass("new unread");
 }
 
@@ -214,7 +206,6 @@ function read_thing(elem) {
         $(t).removeClass("unread");
     }
 
-    alterUnreadCount(-1);
     $.request("read_message", {"id": $(t).thing_id()});
 }