Handle <source media> and <img sizes> with the new code.
Created attachment 463674 [details] wip
Created attachment 463675 [details] wip
Created attachment 463690 [details] Patch
<rdar://problem/102647341>
Created attachment 463710 [details] Patch
Committed 256993@main (ba11d60c7b4c): <https://commits.webkit.org/256993@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 463710 [details].