CrossOrigin on snaps as we don't know where they're coming from
Revert "CrossOrigin on snaps as we don't know where they're coming from"

This reverts commit c436d9aa57fba82fa474c0e53db868d2dd285045.
CrossOrigin on snaps as we don't know where they're coming from
Merge pull request #4042 from guardian/facia-snap-ajax

Facia snap ajax