erp5_web_js_style: reduce page reload

See merge request !1457
6 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

00:46:15

passed ERP5.PerformanceTest-Master

00:24:23

failed ERP5.UnitTest-Master

01:49:08

failed ERP5.UnitTest-Master.Medusa

02:20:18

passed SlapOS.Eggs.UnitTest-Master.Python2

00:15:05

passed SlapOS.Eggs.UnitTest-Master.Python3