title: Leaflet MarkerCluster with GeoJson
body: <p>I am currently working on a Leaflet Project where I use external geojson files as data input. Since the json contains a lot of objects I would like to use the <code>MarkerCluster</code> plugin which I got from Mappbox:</p>
  
  <pre><code>&lt;script src='https://api.tiles.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v0.4.0/leaflet.markercluster.js'&gt;&lt;/script&gt;
  &lt;link href='https://api.tiles.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v0.4.0/MarkerCluster.css' rel='stylesheet' /&gt;
  &lt;link href='https://api.tiles.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v0.4.0/MarkerCluster.Default.css' rel='stylesheet' /&gt;
  </code></pre>
  
  <p>Displaying the json-layer without the clustering works just fine, but if i try to assign it to the cluster nothing is displayed.</p>
  
  <pre><code>var markersBar = L.markerClusterGroup();        
  var barLayer = new L.GeoJSON.AJAX("json/eat_drink/bar.geojson", {
      pointToLayer: function(feature, latlng) {
          var icon = L.icon({
                          iconSize: [27, 27],
                          iconAnchor: [13, 27],
                          popupAnchor:  [1, -24],
                          iconUrl: 'icon/' + feature.properties.amenity + '.png'
                          });
          return L.marker(latlng, {icon: icon})
      }, 
      onEachFeature: function(feature, layer) {
          layer.bindPopup(feature.properties.name + ': ' + feature.properties.opening_hours);
      }
  });
  markersBar.addLayer(barLayer);
  console.log(markersBar);
  map.addLayer(markersBar);
  </code></pre>
  
  <p>The console.log output lets me assume that there are no objects, but I don't get it why.</p>
  
  <pre><code>Object { options: Object, _featureGroup: Object, _leaflet_id: 24, _nonPointGroup: Object, _inZoomAnimation: 0, _needsClustering: Array[0], _needsRemoving: Array[0], _currentShownBounds: null, _queue: Array[0], _initHooksCalled: true }
  </code></pre>
  
  <p>What am I doing wrong? </p>