WebKit iOS 15.0 Beta 4 to Beta 5 API Differences

WKFoundation.h

Removed #def WK_API_AVAILABLE

Removed #def WK_API_UNAVAILABLE

Removed #def WK_CLASS_AVAILABLE

Removed #def WK_API_DEPRECATED

Removed #def WK_API_DEPRECATED_WITH_REPLACEMENT

Removed #def WK_CLASS_DEPRECATED_WITH_REPLACEMENT