Add @struct annotation for simple classes

src/ol/kinetic.js

@@ -13,6 +13,7 @@ goog.require('ol.animation');
  * @param {number} minVelocity Minimum velocity (pixels/millisecond).
  * @param {number} delay Delay to consider to calculate the kinetic
  *     initial values (milliseconds).
+ * @struct
  * @todo stability experimental
  */
 ol.Kinetic = function(decay, minVelocity, delay) {