display-capture is detected as an invalid feature-policy directive

[evilaliv3]

While implementing the Feature-Policy header in Globaleaks (https://github.com/globaleaks/GlobaLeaks/issues/2667) and retesting it with https://securityheaders.com/ i just found out that display-capture is detected as an invalid feature-policy directive.

This could be retested using: https://securityheaders.com/?q=try.globaleaks.org&followRedirects=on

[Malvoz]

There are potentially more features missing, see:

• Standardized features
• Proposed features
• Experimental features