The tests work correctly in Epiphany, but not in the WebKit build,
where the native X25519 implementation throws non-standard errors on
importKey (DataError) and generateKey (OperationError).
Patching this would be simply a matter of catching such errors and falling back
to the JS implementation, but since only the CI WebKit build seems to be
affected, we prefer not to relax fallback checks in the context of crypto
operations without issues reported in the wild.
We were previously testing the webkit engine on Linux, which however relies on a
different WebCrypto API implementation compared to the macOS version (behind Safari).
Also, increase mocha timeouts, as the argon2 memory-heavy test takes longer in Firefox.
To have tests work Browserstack Safari (also below iOS 15), as the tests are run in an iframe,
rewriting localhost as hostname, making WebCrypto not available.
We keep HTTP for the non-browserstack tests so that in local testing,
generating self-signed certs is not required.
