function _onNodesAdded(nodes) {
        var i;
        for (i = 0; i < nodes.length; i++) {
            //check for Javascript files
            if (Utils.isExternalScript(nodes[i])) {
                _transport.send(JSON.stringify({
                    method: 'ScriptAdded',
                    src: nodes[i].src
                }));
            }
            //check for stylesheets
            if (Utils.isExternalStylesheet(nodes[i])) {
                CSS.checkForStylesheetLoaded(nodes[i].href);
            }
        }
    }
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.