code: function pop_local_dialects(lexer, list) {
    if(list && list.length > 0) {
      // we go in reverse order since the most recently
      // used (pushed) dialects will be at the end
      for(var i = list.length-1; i >= 0; i--) {
        if(list[i].dialect) {
          unuse_dialect(list[i].dialect, lexer);
        }
      }
    }
  }
docs: pop any local dialects enabled within the scope of the
  provided list.
  
  note:  here we intentionally look just one level down at
  the *direct* children of the list, since "grandchildren"
  have scopes of their own that are "popped" separately.