Fix 'Shift' DragZoom in default interactions, use zoomDuration

This fix allows the DragZoom interaction created in the default
interactions to use the zoom duration defined in the options, if
set.

externs/olx.js

@@ -2366,7 +2366,7 @@ olx.interaction.DragRotateOptions.prototype.duration;
 /**
  * @typedef {{condition: (ol.events.ConditionType|undefined),
  *     duration: (number|undefined),
- *     style: ol.style.Style}}
+ *     style: (ol.style.Style|undefined)}}
  * @api
  */
 olx.interaction.DragZoomOptions;
@@ -2392,7 +2392,7 @@ olx.interaction.DragZoomOptions.prototype.duration;
 
 /**
  * Style for the box.
- * @type {ol.style.Style}
+ * @type {ol.style.Style|undefined}
  * @api
  */
 olx.interaction.DragZoomOptions.prototype.style;