Current search reveals usage of 'mediawiki.ui.icon' module in
Phase 1
- ULS
- MMV
- Popups
- Minerva and MobileFrontend
- Mark module as deprecated
Phase 2 - all usages
- ContentTranslation (covered in T340259)
- On April 29th we (Bartosz, Jon Robson) removed support for the unused mw-ui-icon-small and mw-ui-icon-flush-top and mw-ui-icon-flush-left to avoid further adoption.
Phase 3
- Flow/includes/View.php <doing>
- Example skin
- Remove 'mediawiki.ui.icon' module
All of above usages should be removed and replaced by Codex (/OOUI) icon modules. And the module itself be removed as result.