compositing different-origin layers in mapbox.js

<!DOCTYPE html>
<html>
<head>
  <script src='https://api.tiles.mapbox.com/mapbox.js/v0.6.7/mapbox.js'></script>
  <link href='https://api.tiles.mapbox.com/mapbox.js/v0.6.7/mapbox.css' rel='stylesheet' />
  <style>
    body { margin:0; padding:0; }
    #map { position:absolute; top:0; bottom:0; width:100%; }
  </style>
</head>
<body>
<div id='map'>
</div>
<script>
var m = mapbox.map('map');

//Define CartoDB tilejson
var communes = mapbox.layer().tilejson({ 
        version: '1.0.0', 
        scheme: 'xyz', 
        tiles: ['https://dai.cartodb.com/tiles/ag_2011_commune3/{z}/{x}/{y}.png'],
        grids: ['https://dai.cartodb.com/tiles/ag_2011_commune3/{z}/{x}/{y}.grid.json'] 
    });
//Add layers to map
m.addLayer(new mapbox.layer().id('landplanner.map-pd5ea4xu'));
m.addLayer(communes);
m.addLayer(new mapbox.layer().id('landplanner.map-lronacbg'));

m.ui.attribution.add()
    .content('Data by <a href="https://openstreetmap.org">OpenStreetMap</a> Contributors, under <a href="https://creativecommons.org/licenses/by-sa/3.0">CC BY SA</a>.');
m.ui.zoomer.add();
m.ui.zoombox.add();
m.ui.hash.add();
m.zoom(9).center({lat: 34.797408767572485, lon: -2.38330078125});
</script>
</body>
</html>

Modified http://api.tiles.mapbox.com/mapbox.js/v0.6.7/mapbox.js to a secure url

https://api.tiles.mapbox.com/mapbox.js/v0.6.7/mapbox.js