<rdar://113654067> TextBreakIteratorCache is a global singleton, so we shouldn't try to use it from Worker threads.
Pull request: https://github.com/WebKit/WebKit/pull/16913
Committed 267175@main (3e4dfc234c15): <https://commits.webkit.org/267175@main> Reviewed commits have been landed. Closing PR #16913 and removing active labels.