Support for the Feature-Policy header

[stof]

See https://scotthelme.co.uk/a-new-security-header-feature-policy/ for an introduction to this header

[Deleted user]

Here are some additional links, for your convenience:

• https://wicg.github.io/feature-policy/
• https://developers.google.com/web/updates/2018/06/feature-policy
• https://caniuse.com/#search=feature-policy