gistfile1.txt

var content = document.getElementById("content");

window.addEventListener("message", function(event) {
  var debuggee = event.ports[0];
  volcan.connect(debuggee).
    then(listTabs).
    then(getCurrentStyleSheets).
    then(writeStyleSheetsLength);
});

function listTabs(root) {
  return root.listTabs();
}

function getCurrentStyleSheets(tabList) {
  var selectedTab = tabList.tabs[tabList.selected];
  return selectedTab.styleSheetsActor.getStyleSheets();
}

function writeStyleSheetsLength(stylesheets) {
  content.textContent = stylesheets.length;
}