Since there's no way to edit non-text resources (e.g. images, fonts, etc.), we should instead ask for the user to upload a new file before creating the override.
Created attachment 382960 [details]
Comment on attachment 382960 [details]
Clearing flags on attachment: 382960
Committed r252200: <https://trac.webkit.org/changeset/252200>
All reviewed patches have been landed. Closing bug.