WPT details: css/css-fonts/generic-family-keywords-002.html
Remove support for the font-family value "-webkit-standard". This essentially behaves as an alias to the proprietary keyword "-webkit-body" and is only exposed as historical implementation details inherited from WebKit.
The "-webkit-standard" name is used internally to describe a default font family that can be configured via a user preference. It's implicitly used internally (e.g. for initial or fallback font) or explicitly by authors via the proprietary name "-webkit-body". However because of how this is implemented, authors can also just specify "-webkit-standard" and obtain similar web-exposed behavior. Removing special behavior for these proprietary value will improve alignment with the CSS specifications and Firefox.