Remove AcceleratedCompositingForFilters setting, it's always off

R=abarth, senorblanco
BUG=401144

Review URL: https://codereview.chromium.org/448753005

git-svn-id: svn://svn.chromium.org/blink/trunk@179660 bbb929c8-8fbe-4397-9dbb-9b2b20218538