We no longer have CSS property names neither value keywords depending on compile flag conditions, thus we can safely remove its support.

BUG=314055

Review URL: https://codereview.chromium.org/57813007

git-svn-id: svn://svn.chromium.org/blink/trunk@161868 bbb929c8-8fbe-4397-9dbb-9b2b20218538