Unregister image listeners when disposing of a tile

src/ol/imagetile.js

@@ -64,6 +64,15 @@ ol.ImageTile = function(tileCoord, state, src, crossOrigin, tileLoadFunction) {
 goog.inherits(ol.ImageTile, ol.Tile);
 
 
+/**
+ * @inheritDoc
+ */
+ol.ImageTile.prototype.disposeInternal = function() {
+  this.unlistenImage_();
+  goog.base(this, 'disposeInternal');
+};
+
+
 /**
  * @inheritDoc
  * @api