Update CSP and Referrer-Policy with issues found by Mozilla Observatory. (#987)
Update CSP and Referrer-Policy with issues found by Mozilla Observatory. (#987)

* Update CSP and Referrer-Policy with issues found by Mozilla Observatory.

* Revert unwanted changes.

testbhearsum/balrog,testbhearsum/balrog,testbhearsum/balrog,testbhearsum/balrog