Function difft::diff::sliders::push_unchanged_to_descendant

fn push_unchanged_to_descendant<'a>(
    root: &'a Syntax<'a>,
    inner: &'a Syntax<'a>,
    change_map: &mut ChangeMap<'a>
)

Given a nested list where the root delimiters are unchanged but the inner list’s delimiters are novel, mark the inner list as unchanged instead.