code: function () {
                  var added = {},
                      current,
                      newStatus;
  
                  current = this.stylesheets;
                  newStatus = related().stylesheets;
  
                  Object.keys(newStatus).forEach(function (v, i) {
                      if (!current[v]) {
                          added[v] = newStatus[v];
                      }
                  });
  
                  Object.keys(added).forEach(function (v, i) {
                      _transport.send(JSON.stringify({
                          method: "StylesheetAdded",
                          href: v,
                          roots: [added[v]]
                      }));
                  });
  
                  this.stylesheets = newStatus;
              }
docs: Send a notification for the stylesheet added and
  its import-ed styleshets based on document.stylesheets diff
  from previous status. It also updates stylesheets status.