Make changes suggested during the review

src/ol/render/canvas/canvasreplay.js

@@ -1180,6 +1180,10 @@ ol.render.canvas.PolygonReplay = function(tolerance, maxExtent, resolution) {
     miterLimit: undefined
   };
 
+  /**
+   * @private
+   * @type {boolean}
+   */
   this.rightHanded_ = false;
 
 };

src/ol/render/renderfeature.js

@@ -86,7 +86,7 @@ ol.render.Feature.prototype.getEnds = function() {
  * @api
  */
 ol.render.Feature.prototype.getExtent = function() {
-  if (!goog.isDef(this.extent_)) {
+  if (!this.extent_) {
     this.extent_ = this.type_ === ol.geom.GeometryType.POINT ?
         ol.extent.createOrUpdateFromCoordinate(this.flatCoordinates_) :
         ol.extent.createOrUpdateFromFlatCoordinates(