Remove the :-webkit-full-screen-document pseudo class

It is virtually unused in the wild, according to use counter data:
https://www.chromestatus.com/metrics/feature/timeline/popularity/627

Nothing similar exists in the spec or is likely to ever be added.

BUG=402378

Review URL: https://codereview.chromium.org/1233503003

git-svn-id: svn://svn.chromium.org/blink/trunk@198966 bbb929c8-8fbe-4397-9dbb-9b2b20218538
12 files changed