Fix the Renamer to preserve builtin structure member names.
Fix the HLSL writer to emit the modf / frexp result type even if there is no private / function storage usage of the types.
Fixed: chromium:1236161
Change-Id: I93b9d92980682f9a9cb090d07b04e4c3f6a2f705
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/60922
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Ben Clayton