Safari Technology Preview 252 adds @supports named-feature(), unprefixed user-select and two accessible-name fixes

WebKit's 11 September preview adds a named-feature() function to @supports, exposes CSSConditionRule.supports and CSSMediaRule.matches on the CSSOM, ships the unprefixed user-select property, allows percentage values in text-decoration-inset, and cleans up two accessible-name bugs around display: contents and list markers.