Rename AbstractFrame to Frame, now that the subclasses are LocalFrame and RemoteFrame.
Pull request: https://github.com/WebKit/WebKit/pull/11467
Committed 261612@main (7651b3eb50d3): <https://commits.webkit.org/261612@main> Reviewed commits have been landed. Closing PR #11467 and removing active labels.
<rdar://problem/106679999>