Fix tile_start_off calculations for extremely large frame sizes. Merge upstream fix: <https://code.videolan.org/videolan/dav1d/-/commit/2b475307dc11be9a1c3cc4358102c76a7f386a51> <rdar://124700924>
Pull request: https://github.com/WebKit/WebKit/pull/25959
Committed 276207@main (4c23f1a14c60): <https://commits.webkit.org/276207@main> Reviewed commits have been landed. Closing PR #25959 and removing active labels.