Remove all the NETBSD guards as we do not build nor test on NetBSD.

BUG=286645
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/23536039

Patch from Laszlo Gombos <l.gombos@samsung.com>.

git-svn-id: svn://svn.chromium.org/blink/trunk@157441 bbb929c8-8fbe-4397-9dbb-9b2b20218538