Remove the force-enable of deferred filters.

Note: this should land after the Chrome-side change which enables the
feature from from Chrome: https://codereview.chromium.org/260383005/

BUG=368265

Review URL: https://codereview.chromium.org/261063006

git-svn-id: svn://svn.chromium.org/blink/trunk@173249 bbb929c8-8fbe-4397-9dbb-9b2b20218538