let the importer ignore incoming script tags
This fixes an issue with the testcafe test runner, where it inserted a script
tag into the HTML body
tag, causing the editor to crash, as it was trying to decipher a js function instead of text.
Should also be good more generally, as this line is blocking script tags in general.
I'd test this with Editoria, Xpub-Collabra, as well as the latter's test runner to check that all is ok.