[clang] [analyzer] Fix false negative when accessing a nonnull property from … (PR #67563)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun approved this pull request.

Looks good, thanks! I think a comment about how the types in the AST already has the nullability propagated correctly might be helpful for the future readers, otherwise it looks good to me!

https://github.com/llvm/llvm-project/pull/67563