Cross-origin exposure of CSRF token

Jenkins uses the https://github.com/jenkinsci/staplerStapler web framework for HTTP request handling. Stapler provides an HTTP endpoint serving dynamically generated JavaScript resources. In Stapler 1839.ved17667baeb5 through 2107.v8dfcbe8ed317 both inclusive, except 2088.2093.vd7c3e58008a6,...