This will help ensuing the decoding mode heuristics are working as expected. It will be used in writing a layout test for bug 270330.
<rdar://problem/125133851>
Pull request: https://github.com/WebKit/WebKit/pull/26223
Committed 276451@main (81c32dcdf889): <https://commits.webkit.org/276451@main> Reviewed commits have been landed. Closing PR #26223 and removing active labels.