Revert "Don't clear the unread count of 404'd threads until they're actually visited."

This reverts commit 528b6fc4b1fd63ed3d807e490b0f1fb42bcccb3b.

src/Monitoring/ThreadWatcher.coffee

@@ -259,6 +259,8 @@ ThreadWatcher =
         ThreadWatcher.db.delete {boardID, threadID}
       else
         data.isDead = true
+        delete data.unread
+        delete data.quotingYou
         ThreadWatcher.db.set {boardID, threadID, val: data}
 
       ThreadWatcher.refresh()