[clang-tidy] Replace redundant checks with an assert().
[clang-tidy] Replace redundant checks with an assert().

findStyleKind is only called if D is an explicit identifier with a name,
so the checks for operators will never return true. The explicit assert()
enforces this invariant.

Differential Revision: https://reviews.llvm.org/D52179

git-svn-id: a34e9779ed74578ad5922b3306b3d80a0c825546@342514 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra