Applies to all Windows because we currently don't have a way to check
which version we're on. The fallback to the old compiler is generating
a warning. This test was being overly conservative. Also updates a few
message strings.

Bug: chromium:920704
Change-Id: If83677881e85d6a6f9ad98b33cd5f7d917bbec6b
Reviewed-on: https://chromium-review.googlesource.com/c/1492311
Commit-Queue: Jamie Madill <jmadill@google.com>
Reviewed-by: Jamie Madill <jmadill@google.com>