ReverseChronologicalPager pages have list headers grouping by date
These list headers are added to the HTML but hidden by default.
They are needed for the mobile version which displays headers
for better scannability.
However the change will only display on:
- Special:Contributions
- history page
- Special:MergeHistory
Bug: T298638
Change-Id: Iaa55eab57f761c9be780aba79cf2b9b212d91657