title: Leaflet mapbox.dark theme is not working, how can get dark theme
body: <p>I have been using leaflet to show map in my website, which is in dark mode, but until recently, I found dark mode in leaflet map stopped working at all,</p>
  <p>This is my code,</p>
  <pre><code>this.map = L.map('dv-map', {
              minZoom: this.props.minZoom,
              maxZoom: this.props.maxZoom
          }).setView(this.props.center, this.props.initLevel);
          L.tileLayer('https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}.png?access_token=' + this.props.mapBoxToken, {
                  maxZoom: this.props.maxZoom,
                  id: 'mapbox.dark'
              })
              .addTo(this.map);
  </code></pre>
  <p>I tested other id, such as mapbox.streets, mapbox.satellite etc., still fine, only dark is not working at all.</p>
  <p>Can anybody tell me how to prvoide dark mode for the leaflet map?</p>
  <p>Thanks</p>