instead of re-computing
Created attachment 439982 [details] Patch
Created attachment 439988 [details] Patch
Created attachment 439989 [details] Patch
Created attachment 440025 [details] Patch
Committed r283485 (242458@main): <https://commits.webkit.org/242458@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 440025 [details].
<rdar://problem/83819509>