Move data members specific to ElementRareData out of NodeRareData. Those were put in NodeRareData for better packing but we can achieve the same packing by rendering data members.
Pull request: https://github.com/WebKit/WebKit/pull/11131
Committed 261308@main (11ece517da22): <https://commits.webkit.org/261308@main> Reviewed commits have been landed. Closing PR #11131 and removing active labels.
<rdar://problem/106345664>