code: function absolutize(token, options, context) {
      var adapter = options.adapter;
  
      //TODO better check if context is document
      var hasContext =
          !!context &&
          !!context.length &&
          context.every(function(e) {
              return e === PLACEHOLDER_ELEMENT || !!adapter.getParent(e);
          });
  
      token.forEach(function(t) {
          if (t.length > 0 && isTraversal(t[0]) && t[0].type !== "descendant") {
              //don't return in else branch
          } else if (hasContext && !includesScopePseudo(t)) {
              t.unshift(DESCENDANT_TOKEN);
          } else {
              return;
          }
  
          t.unshift(SCOPE_TOKEN);
      });
  }
docs: CSS 4 Spec (Draft): 3.3.1. Absolutizing a Scope-relative Selector http://www.w3.org/TR/selectors4/#absolutizing