Some cleanups to FeatureSchemas. Also reduce template arguments in Evaluator.
<rdar://problem/101381659>
Created attachment 463115 [details] Patch
Commit message contains (OOPS!), blocking PR #None
Created attachment 463138 [details] Patch for landing
Committed 255819@main (e1cd9d97b6c9): <https://commits.webkit.org/255819@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 463138 [details].