Remove PseudoIds for fullscreen

PseudoIds are for pseudo elements, not pseudo classes like the full screen 
things and these pseudoIds are never used.

Review URL: https://codereview.chromium.org/127193004

git-svn-id: svn://svn.chromium.org/blink/trunk@164693 bbb929c8-8fbe-4397-9dbb-9b2b20218538