Improve PlatformMouseEvent constructor to replace four bool args with OptionSet<PlatformEvent::Modifier>.
<rdar://problem/102548165>
Pull request: https://github.com/WebKit/WebKit/pull/6672
Committed 256892@main (809039232b9a): <https://commits.webkit.org/256892@main> Reviewed commits have been landed. Closing PR #6672 and removing active labels.