Allow load cheerio using existing domhandler (not only string)

I need to load cheerio from existing dom to prevent parsing same content second time after it was loaded from web. Example usage:

    var cheerio = require('cheerio');
    var DomHandler = htmlparser2.DomHandler;
    var domHandler = new DomHandler(function(error, dom) {
        var $ = cheerio.load(dom)
    });
    // ... load dom
This is used in cheerio parser plugin in iframely: https://github.com/itteco/iframely/blob/develop/lib/plugins/system/cheerio.js