function applyMarkedSelectors(rule) {
  if (rule.$$markedSelectors) {
    rule.selectors = rule.$$markedSelectors;
  }
  if (rule._other) {
    applyMarkedSelectors(rule._other);
  }
}
Apply filtered selectors to a rule from a previous markOnly run.
@private
@param {css.Rule} rule The Rule to apply marked selectors to (if they exist).