Windows 10 Version 1703 / Firefox 55.03
Chrome and Firefox apparently don't treat <strong> the same way when a parent style is already in bold.
.oo-ui-buttonElement > .oo-ui-buttonElement-button has bold so:
- Chrome cancels .oo-ui-buttonElement > .oo-ui-buttonElement-button and only render <strong>MediaWiki:Rcfilters-other-review-tools</strong> as font-wright:bold;
- Firefox cumulates .oo-ui-buttonElement > .oo-ui-buttonElement-button and <strong> and renders MediaWiki:Rcfilters-other-review-tools as font-wright:bolder;