MAGETWO-53299: "Go Today" button is not working for dates range component

- name and getTimezoneDate method refactoring

Author: iivashchenko

lib/web/mage/calendar.js

@@ -35,7 +35,7 @@
          * in order to have ability to know actual store time even if page hadn't been reloaded
          * @returns {Date}
          */
-        _getTimezoneDateDatepicker: function () {
+        _getTimezoneDate: function () {
             // local time in ms
             var ms = Date.now(),
                 options = $.calendarConfig ? $.calendarConfig : {};
@@ -58,7 +58,7 @@
          * @param {String|Object} target - the target input field or division or span
          */
         _setTimezoneDateDatepicker: function (target) {
-            this._setDateDatepicker(target, this._getTimezoneDateDatepicker());
+            this._setDateDatepicker(target, this._getTimezoneDate());
         }
     });
 
@@ -120,7 +120,7 @@
              * @return {String} html template
              */
             $.datepicker.constructor.prototype._generateHTML = function (inst) {
-                var today = this._getTimezoneDateDatepicker(),
+                var today = this._getTimezoneDate(),
                     isRTL = this._get(inst, 'isRTL'),
                     showButtonPanel = this._get(inst, 'showButtonPanel'),
                     hideIfNoPrevNext = this._get(inst, 'hideIfNoPrevNext'),
@@ -396,7 +396,7 @@
          * @return {Object} date
          */
         getTimezoneDate: function () {
-            return this.element[this._picker()]('getTimezoneDate');
+            return datepickerPrototype._getTimezoneDate.call(this);
         }
     });
 
@@ -549,10 +549,9 @@
      * @param {Object} el
      */
     $.datepicker._gotoToday = function (el) {
-        var pickerObject = $(el);
 
         //Set date/time according to timezone offset
-        pickerObject.datepicker('setTimezoneDate')
+        $(el).datepicker('setTimezoneDate')
             // To ensure that user can re-select date field without clicking outside it first.
             .blur();
     };