WebNode doesn't report "Blocked access to external URL" error when needed.
E.g., you can try this DRT test to reproduce:
fast/workers/worker-crash-with-invalid-location.html
It also seems that it is not fired at all in some cases. E.g., FF throws "Access to restricted URI denied" when WebWorker tries to import script from "http://" origin while the script itself is run from "file://". WebNode doesn't do this; I think this is connected.
E.g., you can try this DRT test to reproduce:
fast/workers/worker-crash-with-invalid-location.html
It also seems that it is not fired at all in some cases. E.g., FF throws "Access to restricted URI denied" when WebWorker tries to import script from "http://" origin while the script itself is run from "file://". WebNode doesn't do this; I think this is connected.