code: function (node, selText, cssText) {
      if(!cssText) return
      // get parent to add
      var parent = getParent(node);
      var parentRule = node.parentRule;
      if (validParent(node))
        return node.omRule = addCSSRule(parent, selText, cssText, node)
      else if (parentRule) {
        // for old IE not support @media, check mediaEnabled, add child nodes
        if (parentRule.mediaEnabled) {
          [].concat(node.omRule).forEach(removeOneRule);
          return node.omRule = addCSSRule(parent, selText, cssText, node)
        } else if (node.omRule) {
          node.omRule.forEach(removeOneRule);
          delete node.omRule;
        }
      }
    }
docs: helper function for addNormalrule