This was the initial design to fix bug 265363. But this part was reverted because of a memory regression. It turned out this memory regression was happening because the decoding threads were not deleted.
<rdar://problem/128738620>
Pull request: https://github.com/WebKit/WebKit/pull/29115
Committed 279710@main (b6e2e8c13838): <https://commits.webkit.org/279710@main> Reviewed commits have been landed. Closing PR #29115 and removing active labels.