There's already a FIXME for this issue in the code (https://github.com/WebKit/WebKit/blob/5870261ff9b3f700cae3614190213e0dc5f0477c/Source/WTF/wtf/PlatformHave.h#L439) but I was unable to find a Bugzilla issue for this. The name of HAVE_SAFARI_SERVICES_FRAMEWORK implies it does not exist in macOS, but WebKit is simply not using it, so it would make more sense as USE_SAFARI_SERVICES_FRAMEWORK.
<rdar://problem/116958630>