Rename private attribute _element to _el

Change-Id: I9c7a31bd6844636737ffa6456562b997f5e370a3
diff --git a/dev/js/src/datepicker.js b/dev/js/src/datepicker.js
index 61f6a8b..c2b0570 100644
--- a/dev/js/src/datepicker.js
+++ b/dev/js/src/datepicker.js
@@ -116,7 +116,7 @@
      */
     show : function (year, month) {
 
-      const e = this._element = d.createElement('div');
+      const e = this._el = d.createElement('div');
       e.setAttribute('tabindex', 0);
       e.style.outline = 0;
       e.classList.add('datepicker');
@@ -170,7 +170,7 @@
 
       t._input.focus();
 
-      return t._element;
+      return t._el;
     },
 
     _stringHelper : function () {
@@ -213,7 +213,7 @@
      * Get the HTML element associated with the datepicker.
      */
     element : function () {
-      return this._element;
+      return this._el;
     },