js/leaflet.markercluster.js
function (storageArray) {
    storageArray = storageArray || [];

    for (var i = this._childClusters.length - 1; i >= 0; i--) {
      this._childClusters[i].getAllChildMarkers(storageArray);
    }

    for (var j = this._markers.length - 1; j >= 0; j--) {
      storageArray.push(this._markers[j]);
    }

    return storageArray;
  }
function (storageArray) {
    storageArray = storageArray || [];

    for (var i = this._childClusters.length - 1; i >= 0; i--) {
      this._childClusters[i].getAllChildMarkers(storageArray);
    }

    for (var j = this._markers.length - 1; j >= 0; j--) {
      storageArray.push(this._markers[j]);
    }

    return storageArray;
  }
Recursively retrieve all child markers of this cluster