erp5_web_js_style: add compatibility with google cache

7 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:57:08

passed ERP5.PerformanceTest-Master

00:24:19

failed ERP5.UnitTest-Master

failed ERP5.UnitTest-Master.Medusa

02:48:17

passed SlapOS.Eggs.UnitTest-Master.Python2

00:32:04

passed SlapOS.Eggs.UnitTest-Master.Python3

00:10:38

failed ERP5.UnitTest-Master

02:33:38