More variable font options for the macOS system-ui font in Chromium 83

Catalina brings a new united variable system font to macOS. * Updated The 'system-ui' section of the CSS Fonts Module Level 4 spec defines a system-ui font keyword that allows developers to use the built-in, turbo-optimized, localized, mega-high-quality, no-download-needed, default operating system font right in their sites and apps.