Replace goog.nullFunction with ol.nullFunction

src/ol/source/source.js

@@ -1,6 +1,7 @@
 goog.provide('ol.source.Source');
 goog.provide('ol.source.State');
 
+goog.require('ol');
 goog.require('ol.Attribution');
 goog.require('ol.Object');
 goog.require('ol.proj');
@@ -92,8 +93,7 @@ goog.inherits(ol.source.Source, ol.Object);
  * @return {T|undefined} Callback result.
  * @template T
  */
-ol.source.Source.prototype.forEachFeatureAtCoordinate =
-    goog.nullFunction;
+ol.source.Source.prototype.forEachFeatureAtCoordinate = ol.nullFunction;
 
 
 /**

src/ol/source/tilesource.js

@@ -4,6 +4,7 @@ goog.provide('ol.source.TileOptions');
 
 goog.require('goog.asserts');
 goog.require('goog.events.Event');
+goog.require('ol');
 goog.require('ol.Attribution');
 goog.require('ol.Extent');
 goog.require('ol.TileCache');
@@ -244,7 +245,7 @@ ol.source.Tile.prototype.getTileCoordForTileUrlFunction =
  * @param {number} x Tile coordinate x.
  * @param {number} y Tile coordinate y.
  */
-ol.source.Tile.prototype.useTile = goog.nullFunction;
+ol.source.Tile.prototype.useTile = ol.nullFunction;
 
 
 

src/ol/source/vectorsource.js

@@ -11,6 +11,7 @@ goog.require('goog.events');
 goog.require('goog.events.Event');
 goog.require('goog.events.EventType');
 goog.require('goog.object');
+goog.require('ol');
 goog.require('ol.Collection');
 goog.require('ol.CollectionEventType');
 goog.require('ol.Extent');
@@ -89,7 +90,7 @@ ol.source.Vector = function(opt_options) {
    * @private
    * @type {ol.FeatureLoader}
    */
-  this.loader_ = goog.nullFunction;
+  this.loader_ = ol.nullFunction;
 
   if (options.loader !== undefined) {
     this.loader_ = options.loader;