Function difft::diff::sliders::push_unchanged_to_ancestor

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

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