Remove gratuitous debug assertions

src/ol/renderer/canvas/canvastilelayerrenderer.js

@@ -142,7 +142,6 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame = function(
       if (!drawableTile(tile) && tile.interimTile) {
         tile = tile.interimTile;
       }
-      goog.DEBUG && console.assert(tile);
       if (drawableTile(tile)) {
         tilesToDrawByZ[z][tile.tileCoord.toString()] = tile;
         continue;

src/ol/renderer/canvas/canvasvectorlayerrenderer.js

@@ -172,7 +172,6 @@ ol.renderer.canvas.VectorLayer.prototype.forEachFeatureAtCoordinate = function(c
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature !== undefined, 'received a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;

src/ol/renderer/canvas/canvasvectortilelayerrenderer.js

@@ -306,7 +306,6 @@ ol.renderer.canvas.VectorTileLayer.prototype.forEachFeatureAtCoordinate = functi
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature, 'received a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;