Register a CHANGE listener even if tile is loading

This fixes an issue easily reproducible in the side-by-side example where the DOM renderer is not notified when tiles loaded by the WebGL renderer have been received.

src/ol/renderer/dom/domtilelayerrenderer.js

@@ -139,12 +139,10 @@ ol.renderer.dom.TileLayer.prototype.render = function() {
       tilesToDrawByZ[z][key] = tile;
       return;
     } else {
-      if (state != ol.TileState.LOADING) {
       goog.events.listen(tile, goog.events.EventType.CHANGE,
           this.handleTileChange_, false, this);
       tile.load();
     }
-    }
 
     /**
      * Look for already loaded tiles at alternate z that can serve as