Allow tileLoadFunction override for ol.source.Stamen

src/objectliterals.jsdoc

@@ -540,6 +540,8 @@
  * @property {number|undefined} minZoom Minimum zoom.
  * @property {number|undefined} maxZoom Maximum zoom.
  * @property {boolean|undefined} opaque Whether the layer is opaque.
+ * @property {ol.TileLoadFunctionType|undefined} tileLoadFunction Optional
+ *     function to load a tile given a URL.
  * @property {string|undefined} url URL.
  */
 

src/ol/source/stamensource.js

@@ -103,6 +103,7 @@ ol.source.Stamen = function(options) {
     // FIXME uncomment the following when tilegrid supports minZoom
     //minZoom: providerConfig.minZoom,
     opaque: layerConfig.opaque,
+    tileLoadFunction: options.tileLoadFunction,
     url: url
   });