UX: Timeline should jump to the bottom of the post in single-post topics (PR #10503)

Context: https://meta.discourse.org/t/scroll-to-bottom-of-a-topic-with-1-post/161173

Clicking the latest date or dragging the timeline scroller to the bottom in topics with a single lengthy post takes you to the top of that post - even if you’re already there.

This PR attempts to address this issue.

The desired result is that topics with a single lengthy post have a slightly different behaviour. When you click on the latest date (or drag the timeline scroller to the very bottom) you should be taken to the bottom of that post. This is what this PR does.

I’ve tested this in a number of different scenarios and I haven’t seen any regressions in terms of the current functionality. Again, this only affects topics with a single lengthy post.

GitHub

This seems cool to me and something I’ve definitely wanted before.