remove unnecessary utility function

app/assets/javascripts/due_date_select.js.es6

@@ -83,9 +83,8 @@
       this.rawSelectedDate = $(`input[name='${this.fieldName}']`).val();
 
       if (this.rawSelectedDate.length) {
-        // Avoid time zone inconsistency using the utils.createDateObject
-        // method, instead of the native Date object.
-        const dateObj = gl.utils.createDateObject(this.rawSelectedDate);
+        const dateArray = this.rawSelectedDate.split('-').map(v => parseInt(v, 10));
+        const dateObj = new Date(dateArray[0], dateArray[1] - 1, dateArray[2]);
         this.displayedDate = $.datepicker.formatDate('M d, yy', dateObj);
       } else {
         this.displayedDate = 'No due date';

app/assets/javascripts/lib/utils/datetime_utility.js

-/* eslint-disable func-names, space-before-function-paren, wrap-iife, no-var, no-param-reassign, no-cond-assign, comma-dangle, no-unused-expressions, prefer-template, prefer-arrow-callback, padded-blocks, max-len */
+/* eslint-disable func-names, space-before-function-paren, wrap-iife, no-var, no-param-reassign, no-cond-assign, comma-dangle, no-unused-expressions, prefer-template, padded-blocks, max-len */
 /* global timeago */
 /* global dateFormat */
 
@@ -16,19 +16,6 @@
     }
     w.gl.utils.days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
 
-    // createDateObject must be used instead of using native Date object
-    // to create a new Date instance using string as param - '2016-11-10' or
-    // '2016/11/10' in order to avoid time zone inconsistency.
-    w.gl.utils.createDateObject = function(string) {
-      var dateSeparator = string.indexOf('-') > -1 ? '-' : '/';
-
-      var dateArray = string.split(dateSeparator).map(function(dateItem) {
-        return parseInt(dateItem, 10);
-      });
-
-      return new Date(dateArray[0], dateArray[1] - 1, dateArray[2]);
-    };
-
     w.gl.utils.formatDate = function(datetime) {
       return dateFormat(datetime, 'mmm d, yyyy h:MMtt Z');
     };