Use thread safe initialization in cascadeToLastResortAndVariationsFontDescriptor
Created attachment 446473 [details] Patch
This patch wouldn't be needed if bug 234102 pans out.
<rdar://problem/86553131>
Created attachment 461056 [details] Patch
Committed 252670@main (fecb96411739): <https://commits.webkit.org/252670@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 461056 [details].