We can’t resolve relative urls (e.g. for images) in the compiler as
these urls are meant to be loaded in the browser
(unless we would inline images as base64…).
Also, keep `<link rel=“stylesheet”>` in templates that
reference absolute urls with e.g. `http://`. This
behavior was already present for `@import` rules
within stylesheets.
Closes#4740
7dde18b181