Add "json" destination for "connect-src" (#611)

This change explicitly adds the "json" fetch destination to the algorithm deciding which directive must be checked, and it makes "connect-src" responsible for the check.

Author: nicolo-ribaudo

index.bs

@@ -4348,6 +4348,7 @@ this algorithm returns normally if compilation is allowed, and throws a
       ::
         1. Return `worker-src`.
 
+      : "`json`"
       : "`webidentity`"
       ::
         1. Return `connect-src`.