Use ol.Collection#extend in examples

This commit changes the examples to using ol.control.defaults().extend to extend the collection of controls. This is in preparation for a future commit that will remove the 2nd argument to ol.control.defaults. The same is done for ol.interaction.defaults.

examples/navigation-controls.js

@@ -8,7 +8,7 @@ goog.require('ol.source.OSM');
 
 
 var map = new ol.Map({
-  controls: ol.control.defaults({}, [
+  controls: ol.control.defaults().extend([
     new ol.control.ZoomToExtent({
       extent: [
         813079.7791264898,