The DifferenceEngine class in core can now handle inline diffs (provided wikidiff2 is installed). We will drop InlineDiffFormatter and InlineDifferenceEngine from MobileFrontend which cater for 3rd parties. The deprecation notice was added a while back and we've been running this code in production for several months now. All we need to do is remove it.
= Acceptance criteria
[x] The deprecation notice has been pushed out.
[ ] InlineDifferenceEngine is gone from MobileFrontend
[ ] InlineDiffFormatter is gone from MobileFrontend
[ ] No change in display before and after to Special:MobileDiff.
= Developer notes
When testing note you'll need wikidiff2 installed. If you don't after the code removal you will realise that you've been testing code locally that is never used in production and will need to set it up :-).
Note: The removal of MobileDiff will happen later. We are not ready to do that just yet!