Remove goog.isDef from formats

src/ol/format/topojsonformat.js

@@ -26,7 +26,7 @@ goog.require('ol.proj');
  */
 ol.format.TopoJSON = function(opt_options) {
 
-  var options = goog.isDef(opt_options) ? opt_options : {};
+  var options = opt_options ? opt_options : {};
 
   goog.base(this);
 
@@ -251,8 +251,7 @@ ol.format.TopoJSON.readFeatureFromGeometry_ = function(object, arcs,
   var geometry;
   var type = object.type;
   var geometryReader = ol.format.TopoJSON.GEOMETRY_READERS_[type];
-  goog.asserts.assert(goog.isDef(geometryReader),
-      'geometryReader should be defined');
+  goog.asserts.assert(geometryReader, 'geometryReader should be defined');
   if ((type === 'Point') || (type === 'MultiPoint')) {
     geometry = geometryReader(object, scale, translate);
   } else {
@@ -261,10 +260,10 @@ ol.format.TopoJSON.readFeatureFromGeometry_ = function(object, arcs,
   var feature = new ol.Feature();
   feature.setGeometry(/** @type {ol.geom.Geometry} */ (
       ol.format.Feature.transformWithOptions(geometry, false, opt_options)));
-  if (goog.isDef(object.id)) {
+  if (object.id) {
     feature.setId(object.id);
   }
-  if (goog.isDef(object.properties)) {
+  if (object.properties) {
     feature.setProperties(object.properties);
   }
   return feature;
@@ -290,13 +289,13 @@ ol.format.TopoJSON.prototype.readFeaturesFromObject = function(
   if (object.type == 'Topology') {
     var topoJSONTopology = /** @type {TopoJSONTopology} */ (object);
     var transform, scale = null, translate = null;
-    if (goog.isDef(topoJSONTopology.transform)) {
+    if (topoJSONTopology.transform) {
       transform = topoJSONTopology.transform;
       scale = transform.scale;
       translate = transform.translate;
     }
     var arcs = topoJSONTopology.arcs;
-    if (goog.isDef(transform)) {
+    if (transform) {
       ol.format.TopoJSON.transformArcs_(arcs, scale, translate);
     }
     /** @type {Array.<ol.Feature>} */