Use HTTPS where available

src/ol/source/mapquestsource.js

@@ -1,7 +1,6 @@
 goog.provide('ol.source.MapQuest');
 
 goog.require('goog.asserts');
-goog.require('ol');
 goog.require('ol.Attribution');
 goog.require('ol.source.OSM');
 goog.require('ol.source.XYZ');
@@ -32,9 +31,8 @@ ol.source.MapQuest = function(opt_options) {
    */
   this.layer_ = options.layer;
 
-  var protocol = ol.IS_HTTPS ? 'https:' : 'http:';
   var url = goog.isDef(options.url) ? options.url :
-      protocol + '//otile{1-4}-s.mqcdn.com/tiles/1.0.0/' +
+      'https://otile{1-4}-s.mqcdn.com/tiles/1.0.0/' +
       this.layer_ + '/{z}/{x}/{y}.jpg';
 
   goog.base(this, {