This reads the nonce from link elements and Link headers. This was implemented by Chromium in 2017 to be consistent with the HTMLPreloader: https://chromium-review.googlesource.com/c/chromium/src/+/676769/
Pull request: https://github.com/WebKit/WebKit/pull/932
Committed r294819 (250972@main): <https://commits.webkit.org/250972@main> Reviewed commits have been landed. Closing PR #932 and removing active labels.
<rdar://problem/93922243>