Initiate tile load only after registering it as loading

src/ol/tilequeue.js

@@ -119,10 +119,10 @@ ol.TileQueue.prototype.loadMoreTiles = function(maxTotalLoading, maxNewLoads) {
          this.getCount() > 0) {
     tile = /** @type {ol.Tile} */ (this.dequeue()[0]);
     if (tile.getState() === ol.TileState.IDLE) {
-      tile.load();
       this.tilesLoadingKeys_[tile.getKey()] = true;
       ++this.tilesLoading_;
       ++newLoads;
+      tile.load();
     }
   }
 };