[clang] [lld] [llvm] [mlir] [NFC] Use more isa and isa_and_nonnull instead dyn_cast for predicates (PR #137393)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> Hi, this is my first contribution in LLVM. I would like to know ho many approves needed and is there anything else needed on my side? Thanks!

I think they just forgot to check if you have the write access. I think this is good to merge if you fixed the CI or make sure it doesn't relate to this PR.

https://github.com/llvm/llvm-project/pull/137393