Introduce new Vector constructor that takes in a length and a lambda to generate vector items.
Pull request: https://github.com/WebKit/WebKit/pull/18533
Committed 268791@main (ad5bc6db70f6): <https://commits.webkit.org/268791@main> Reviewed commits have been landed. Closing PR #18533 and removing active labels.
<rdar://problem/116410300>