[clang] [clang] Optimize castToDeclContext for 2% improvement in build times (PR #76825)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

Please add a detailed summary for this PR. The summary is what usually goes into the git log and it is important that the git log is useful for quick understanding of changes without having to dig into the details.



https://github.com/llvm/llvm-project/pull/76825