Simplify SmallStringKey in the WidthCache by relying on StringView::hash() instead of duplicating the hashing logic there.
Pull request: https://github.com/WebKit/WebKit/pull/18554
Committed 268799@main (53b95eb35d95): <https://commits.webkit.org/268799@main> Reviewed commits have been landed. Closing PR #18554 and removing active labels.
<rdar://problem/116415418>