Tested with the text link described at https://cup.aihedy.com/addon/inlinedisposition/

Working with Waterfox 56.2.1 on FreeBSD-CURRENT,

$ date ; uname -v
Wed 4 Jul 2018 03:14:50 BST
FreeBSD 12.0-CURRENT #6 r335800: Sat Jun 30 03:35:14 BST 2018 root@momh167-gjp4-hpelitebook8570p-freebsd:/usr/obj/usr/src/amd64.amd64/sys/GENERIC
$ pkg info waterfox | grep Version
Version : 56.2.1.48_1

----

https://discourse.mozilla.org/t/-/17087/198?u=grahamperrin suggests InlineDispositionV2 as an alternative to InlineDisposition.