Add WebCodecs H264 L1T2 support
<rdar://problem/114940765>
Pull request: https://github.com/WebKit/WebKit/pull/17414
Committed 269297@main (f2328d7f963e): <https://commits.webkit.org/269297@main> Reviewed commits have been landed. Closing PR #17414 and removing active labels.
Committed 267815.400@safari-7617-branch (7d0aacb2af3c): <https://commits.webkit.org/267815.400@safari-7617-branch> Reviewed commits have been landed. Closing PR #857 and removing active labels.