Use a unique key for all tile classes

src/ol/ImageTile.js

@@ -39,6 +39,8 @@ class ImageTile extends Tile {
      */
     this.src_ = src;
 
+    this.key = src;
+
     /**
      * @private
      * @type {HTMLImageElement|HTMLCanvasElement}
@@ -70,13 +72,6 @@ class ImageTile extends Tile {
     return this.image_;
   }
 
-  /**
-   * @return {string} Key.
-   */
-  getKey() {
-    return this.src_;
-  }
-
   /**
    * Tracks loading or read errors.
    *

src/ol/VectorTile.js

@@ -63,6 +63,8 @@ class VectorTile extends Tile {
      * @type {string}
      */
     this.url_ = src;
+
+    this.key = src;
   }
 
   /**
@@ -83,13 +85,6 @@ class VectorTile extends Tile {
     return this.features_;
   }
 
-  /**
-   * @return {string} Key.
-   */
-  getKey() {
-    return this.url_;
-  }
-
   /**
    * Load not yet loaded URI.
    */

test/spec/ol/source/vectortile.test.js

@@ -393,7 +393,7 @@ describe('ol.source.VectorTile', function () {
           );
           if (sourceTiles) {
             expect(sourceTiles[0].getKey()).to.be(
-              'spec/ol/data/14-8938-5680.vector.pbf?new'
+              'spec/ol/data/14-8938-5680.vector.pbf?new/14,8938,5680'
             );
             unByKey(key);
             done();