With the latest public beta <https://developer.apple.com/news/?id=2cakrt06>, there are some new {WK,JSC}_{MAC,IOS}_TBA macros that can be replaced with real availability versions in SPI headers.
Pull request: https://github.com/WebKit/WebKit/pull/12619
<rdar://problem/107897109>
Pull request: https://github.com/apple/WebKit/pull/543
Committed 262840@main (156322851446): <https://commits.webkit.org/262840@main> Reviewed commits have been landed. Closing PR #12619 and removing active labels.
Committed 259548.633@safari-7615-branch (5c45d4e6dd20): <https://commits.webkit.org/259548.633@safari-7615-branch> Reviewed commits have been landed. Closing PR #543 and removing active labels.