Drop unwanted dependencies on chromium_tests recipe module

ios and webrtc are not ready to move to chromium/src yet,
which would otherwise be required to move chromium_tests there.

See https://codereview.chromium.org/2146873002 and
https://codereview.chromium.org/2147913002 for similar CLs
from the past.

BUG=584079, 593999

Review-Url: https://codereview.chromium.org/2243853002
14 files changed