html2canvas on firefox, return error "0ms Starting document clone"

Question

My app works fine on Chrome, but on FireFox I get the error "17438313cea 0ms Starting document clone" when trying to convert images using html2canvas library, any help, please

    var iframe = document.createElement('iframe');
    document.body.appendChild(iframe);
    var iframedoc = iframe.contentDocument||iframe.contentWindow.document;
    iframedoc.body.innerHTML = "<div>...</div>";

    // html2canvas 1.0.0-rc.5
    html2canvas(iframedoc.body, {useCORS: true}).then(function (canvas) {
        var paper_size = [80, 297];
        var img = canvas.toDataURL("image/jpeg");
        var pdf = new jsPDF('p', 'mm', paper_size);
        pdf.addImage(img,'jpeg', 0, 0, paper_size[0], 0, undefined,'FAST');
        pdf.save();
        document.body.removeChild(iframe);
    });