Update namespace for TK_AsIs

ast_type_traits namespace was removed in https://reviews.llvm.org/D93244

Change-Id: I93b7cb789085185036f257a764afc3d6ee7c47ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2612589Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842365}

tools/clang/rewrite_raw_ptr_fields/RewriteRawPtrFields.cpp

@@ -1086,7 +1086,7 @@ int main(int argc, const char* argv[]) {
   // TODO(lukasza): It is unclear why |traverse| below is needed.  Maybe it can
   // be removed if https://bugs.llvm.org/show_bug.cgi?id=46287 is fixed.
   match_finder.addMatcher(
-      traverse(clang::ast_type_traits::TK_AsIs,
+      traverse(clang::TraversalKind::TK_AsIs,
                cxxConstructExpr(templated_function_arg_matcher)),
       &affected_expr_rewriter);