The depdency is just missing. The message is used in the code, but
not loaded, resulting in tooltips that show "<ooui-item-remove>".
This is currently an actual issue when playing around with the
AdvancedSearch prototype announced at
https://www.mediawiki.org/wiki/Help:Extension:AdvancedSearch
Change-Id: Ia89f2dd6c89b03fe63d289732ac9221eddf5db99
'oojs-ui.styles.icons-moderation',
],
'messages' => [
+ 'ooui-item-remove',
'ooui-outline-control-move-down',
'ooui-outline-control-move-up',
'ooui-outline-control-remove',