wptserve: Import latest version of wpt-tools.

This revision contains a fix to the "bind_hostname" functionality that makes
it possible to use that, rather than incorrectly overriding the "host" config
to an ip-address.

This fixes {{host}} and things like {{domains[www]}} substitutions for tests
when run with wptserve.

BUG=618616

Review-Url: https://codereview.chromium.org/2563823002
Cr-Commit-Position: refs/heads/master@{#437430}
5 files changed