Add find()/reverseFind()/contains() overloads takes an ASCIILiteral to our String types. These versions are more efficient when the call sites have an ASCIILiteral as they have less branching.
Pull request: https://github.com/WebKit/WebKit/pull/569
<rdar://problem/93365800>
Pull request: https://github.com/WebKit/WebKit/pull/730
Committed r294468 (250730@main): <https://commits.webkit.org/250730@main> Reviewed commits have been landed. Closing PR #730 and removing active labels.