[Web UI] Chat pane jumps around in the presence of threaded replies

[shabbyx]

I see this pretty consistently in the Web UI:

- In a meeting, have people chat (enough for the chat pane to scroll)

- Make sure there are replies to chat messages in threads

- Scroll to the bottom of the chat pane (or be anywhere really, including scroll up and down while the next step happens)

- Have someone else add a chat message anywhere

- Observer that chat pane jumps up automatically every time there is a new message

It looks like Zoom is _trying_ to keep the chat pane focused on the same place when it refreshes with new messages, but miscalculates the scroll position. Given that the jump is always upwards, it's almost as if it doesn't take the reply-in-threads into account when calculating scroll position.