Function style_tree_with_ancestors_vars_stack 

pub(crate) fn style_tree_with_ancestors_vars_stack<'a>(
    root: &'a Node,
    stylesheet: &StyleSheet,
    rule_index: Option<&RuleIndex>,
    ancestors_stack: &mut Vec<AncestorContext<'a>>,
    sibling_index: Option<usize>,
    sibling_count: Option<usize>,
    parent_vars: &Rc<BTreeMap<String, String>>,
    parent_inherited: &Rc<BTreeMap<String, String>>,
    counters_in: &BTreeMap<String, i64>,
    counter_stack_in: &CounterScopeStack,
) -> (StyledNode<'a>, BTreeMap<String, i64>, BTreeSet<String>, CounterScopeStack)