Turn on clang deprecation warnings for Blink.

BUG=322505
R=jochen@chromium.org
TBR=abarth@chromium.org

Review URL: https://codereview.chromium.org/94773002

git-svn-id: svn://svn.chromium.org/blink/trunk@162829 bbb929c8-8fbe-4397-9dbb-9b2b20218538