title: Html2canvas not working highcharts to png doesn't work on Firefox and IE
body: <p>We are using html2canvas.js and canvg.js (@version 2.0.1) and highcharts.js to download a chart into png image.</p>
  
  <p>This works as expected in Chrome, however in IE and Firefox this not working.</p>
  
  <p>Below are screenshots of the download in Chrome, IE and Firefox:</p>
  
  <p>Chrome:
  <a href="https://i.stack.imgur.com/EN0Y9.png" rel="nofollow noreferrer">Chrome image</a></p>
  
  <p>Firefox:
  <a href="https://i.stack.imgur.com/PkCYF.png" rel="nofollow noreferrer">Firefox image</a></p>
  
  <p><strong>code:</strong></p>
  
  <pre><code>var svg = $('#previewImage');
  
  html2canvas(svg, {
    onrendered: function(canvas) {
      $("#previewImage").append(canvas);
      var imgageData = canvas.toDataURL("image/png");
      download(imgageData, filename + '.png');
    }
  });
  }
  
  function download(data, filename) {
    $('#previewImage').css('display', 'none');
    var a = document.createElement('a');
    a.download = filename;
    a.href = data
    document.body.appendChild(a);
    a.click();
    a.remove();
  }
  </code></pre>