Add some type hints in ol.Kinetic

src/ol/kinetic.js

@@ -108,10 +108,15 @@ ol.Kinetic.prototype.pan = function(source) {
   var initialVelocity = this.initialVelocity_;
   var minVelocity = this.minVelocity_;
   var duration = this.getDuration_();
-  var easingFunction = function(t) {
+  var easingFunction = (
-    return initialVelocity * (Math.exp((decay * t) * duration) - 1) /
+      /**
-        (minVelocity - initialVelocity);
+       * @param {number} t T.
-  };
+       * @return {number} Easing.
+       */
+      function(t) {
+        return initialVelocity * (Math.exp((decay * t) * duration) - 1) /
+            (minVelocity - initialVelocity);
+      });
   return ol.animation.pan({
     source: source,
     duration: duration,