Use more smart pointers in the HTML parsing code.
Pull request: https://github.com/WebKit/WebKit/pull/17801
Committed 268278@main (49c1df2a9309): <https://commits.webkit.org/268278@main> Reviewed commits have been landed. Closing PR #17801 and removing active labels.
<rdar://problem/115865960>
It regressed. Bug 264382 – WTFCrash in ~CanMakeCheckedPtrBase of ~EventTarget