js/leaflet.markercluster.js
function (id) {
    var result = null;

    this.eachLayer(function (l) {
      if (L.stamp(l) === id) {
        result = l;
      }
    });

    return result;
  }
function (id) {
    var result = null;

    this.eachLayer(function (l) {
      if (L.stamp(l) === id) {
        result = l;
      }
    });

    return result;
  }
Overrides LayerGroup.getLayer, WARNING: Really bad performance