- removed timestamp parameter. This wasn't totally obvious, previously we were tracking two pieces of state
1. `unreadIndicator.firstUnseenTimestamp`:
the first unseen timestamp for a conversation that exists in the database
2. `unreadIndicator.timestamp`:
the timestamp of the first interaction *after* the unread indicator that fits in the loading window
We don't actually need to track `2` because it was only used in a comparison like:
viewItem.interaction.timestampForSorting >= unreadIndicator.timestamp
But by definition, unreadIndicator.firstUnseenTimestamp is always less than or
equal to unreadIndicator.timestamp. Put into terms of the `sortId` corallary,
the sortId of the first unseen interaction in the database is always less than
or equal to the sortId of the first unseen interaction that fits in the loading
window.
In other words, there's no situation where
viewItem.interaction.sortId >= unreadIndicator.firstUnseenSortId
6f8eddc955