javascript下ie7，ie8的Date Bug的解决

ie9+, chrome firefox opera下 string到Date 使用  new Date("2013-01-01"); 都是ok的。

但在ie7， ie8下 返回NaN

 function parseISO8601(dateStringInRange) {
   var isoExp = /^\s*(\d{4})-(\d\d)-(\d\d)\s*$/,
       date = new Date(NaN), month,
       parts = isoExp.exec(dateStringInRange);  

   if(parts) {
     month = +parts[2];
     date.setFullYear(parts[1], month - 1, parts[3]);
     if(month != date.getMonth() + 1) {
       date.setTime(NaN);
     }
   }
   return date;
 }

parseISO8601('2016-10-01');