Function style::custom_properties::substitute_one_reference

fn substitute_one_reference<'a>(
    css: &'a str,
    url_data: &UrlExtraData,
    custom_properties: &'a ComputedCustomProperties,
    reference: &VarOrEnvReference,
    stylist: &Stylist,
    computed_context: &Context<'_>,
    references: &mut Peekable<Iter<'_, VarOrEnvReference>>,
) -> Result<Substitution<'a>, ()>