User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0

Steps to reproduce:

1. Sync tabs from the first device
2. Open the tab on the other device
3. Read part of the text on the second device
4. Sync tabs again

Actual results:

We have the same tab (the same page) opened on 2 devices with two different reading positions.

Expected results:

I'd like Firefox Sync to synchronize reading position or at least highlight the same tabs (tabs with the same url on 2 or more devices) so I can easily see them in the list.

Ideally it'd be good to be able to close the synced tab on remote device, but as I understood from other discussions it's not easy to implement.

Folding this into bug 1215714, since scroll position is part of the session store data.