• aphront-panel-preview
  • Added in https://we.phorge.it/rP3f11c8a602f0a7567f8a51bc3b1a2dddbd46eec2, usage removed in https://we.phorge.it/rP6bfb101aff20a1f1f0435178e2de044a945676ba and in https://we.phorge.it/rPc05306d746d7e06e3f2a5eb712af89a616abfdc6 by deleting src/applications/differential/view/DifferentialAddCommentView.php
• phabricator-remarkup-mention-disabled
  • Added in https://we.phorge.it/rP45c662e4f795fdd4032167ee8432842b6db8024f, usage removed in https://we.phorge.it/rPf2828481aad6717897dcb211735d59ec0e6ad056 from src/applications/people/remarkup/PhabricatorRemarkupRuleMention.php
• phabricator-remarkup-mention-exists
  • Added in https://we.phorge.it/rP405b05a49014eede90c098a8f9af1e41f5cd76dd, usage removed in https://we.phorge.it/rPf2828481aad6717897dcb211735d59ec0e6ad056 from src/applications/people/remarkup/PhabricatorRemarkupRuleMention.php
• phabricator-remarkup-toc
  • Added in https://we.phorge.it/rP5e486db59d651dc387035dd773891b9deff7d756, usage removed in https://we.phorge.it/rPbf227f77a5dc928f1380e4bc81059f83cfb96548 resp https://we.phorge.it/rPd3546f94c15f27bab707d44d6b8a40e2fdeef6a2
• phabricator-remarkup-toc-header
  • Added in https://we.phorge.it/rP5e486db59d651dc387035dd773891b9deff7d756, usage removed in https://we.phorge.it/rPbf227f77a5dc928f1380e4bc81059f83cfb96548
• remarkup-proxy-image
  • Added in https://we.phorge.it/rP03ebbccbc99fb47037ce84c0707d790af6f762c7, usage removed in https://we.phorge.it/rP9966af50dd5d670f151db6423000fee3836e87c6

Grep the code for each CSS selector (grep --exclude="*.css" -R 'some-search-string' .), also do partial searches, get no results.