Stop using UncheckedLock in ShadowBlur's ScratchBuffer to benefit from Clang Thread Safety Analysis.
Created attachment 429551 [details] Patch
Created attachment 429553 [details] Patch
Committed r277965 (238089@main): <https://commits.webkit.org/238089@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 429553 [details].
<rdar://problem/78418073>