[AST] Migrate away from PointerUnion::dyn_cast (NFC)#124228

kazutakahirata merged 1 commit intollvm:mainllvm/llvm-project:mainfrom

kazutakahirata:cleanup_001_PointerUnion_ByteCodekazutakahirata/llvm-project:cleanup_001_PointerUnion_ByteCodeCopy head branch name to clipboard