> Start with supporting only one version of HTTP, TLS, (X)HTML, CSS and JS and fork them if necessary. The support for different versions that does exist in b

> Start with supporting only one version of HTTP, TLS, (X)HTML, CSS and JS and fork them if necessary. The support for different versions that does exist in browsers tends to be minute: ripping out support for older versions would cut out almost no code, because there's basically nothing specifically handling them. (Heck, the only forks in CSS are for quirks and limited quirks mode, and both of them affect very, very little of the layout engine.)