Remove remaining use of inherits in src

src/ol/source/TileArcGISRest.js

@@ -51,25 +51,25 @@ import {appendParams} from '../uri.js';
  */
 
 
-/**
- * @classdesc
- * Layer source for tile data from ArcGIS Rest services. Map and Image
- * Services are supported.
- *
- * For cached ArcGIS services, better performance is available using the
- * {@link module:ol/source/XYZ~XYZ} data source.
- *
- * @constructor
- * @extends {module:ol/source/TileImage}
- * @param {module:ol/source/TileArcGISRest~Options=} opt_options Tile ArcGIS Rest options.
- * @api
- */
-class TileArcGISRest {
+class TileArcGISRest extends TileImage {
+  /**
+   * @classdesc
+   * Layer source for tile data from ArcGIS Rest services. Map and Image
+   * Services are supported.
+   *
+   * For cached ArcGIS services, better performance is available using the
+   * {@link module:ol/source/XYZ~XYZ} data source.
+   *
+   * @constructor
+   * @extends {module:ol/source/TileImage}
+   * @param {module:ol/source/TileArcGISRest~Options=} opt_options Tile ArcGIS Rest options.
+   * @api
+   */
   constructor(opt_options) {
 
     const options = opt_options || {};
 
-    TileImage.call(this, {
+    super({
       attributions: options.attributions,
       cacheSize: options.cacheSize,
       crossOrigin: options.crossOrigin,
@@ -216,7 +216,5 @@ class TileArcGISRest {
   }
 }
 
-inherits(TileArcGISRest, TileImage);
-
 
 export default TileArcGISRest;