Use extends and super for ImageCanvas

src/ol/ImageCanvas.js

@@ -1,7 +1,6 @@
 /**
  * @module ol/ImageCanvas
  */
-import {inherits} from './util.js';
 import ImageBase from './ImageBase.js';
 import ImageState from './ImageState.js';
 
@@ -16,10 +15,7 @@ import ImageState from './ImageState.js';
  */
 
 
-/**
+class ImageCanvas extends ImageBase {
- * @extends {module:ol/ImageBase}
- */
-class ImageCanvas {
 
   /**
    * @param {module:ol/extent~Extent} extent Extent.
@@ -31,6 +27,10 @@ class ImageCanvas {
    */
   constructor(extent, resolution, pixelRatio, canvas, opt_loader) {
 
+    const state = opt_loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
+
+    super(extent, resolution, pixelRatio, state);
+
     /**
      * Optional canvas loader function.
      * @type {?module:ol/ImageCanvas~Loader}
@@ -38,10 +38,6 @@ class ImageCanvas {
      */
     this.loader_ = opt_loader !== undefined ? opt_loader : null;
 
-    const state = opt_loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
-
-    ImageBase.call(this, extent, resolution, pixelRatio, state);
-
     /**
      * @private
      * @type {HTMLCanvasElement}
@@ -98,7 +94,5 @@ class ImageCanvas {
   }
 }
 
-inherits(ImageCanvas, ImageBase);
-
 
 export default ImageCanvas;