[WebGPU] OOB buffer access as offset is not considered in max vertex counts
<rdar://problem/131387875>
Pull request: https://github.com/WebKit/WebKit/pull/30605
Committed 280789@main (c354673f409e): <https://commits.webkit.org/280789@main> Reviewed commits have been landed. Closing PR #30605 and removing active labels.