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