Since we want most reports to be usable from Workers, we should use a thread-safe string, instead of the more efficient AtomString.
<rdar://problem/100130509>
Pull request: https://github.com/Webkit/WebKit/pull/4494
Committed 254680@main (552bfd33df16): <https://commits.webkit.org/254680@main> Reviewed commits have been landed. Closing PR #4494 and removing active labels.