Remove more dead code from core/ folder

Remove more dead code from core/ folder. Several functions were defined but
never used.

R=eseidel@chromium.org, adamk@chromium.org

Review URL: https://codereview.chromium.org/241643006

git-svn-id: svn://svn.chromium.org/blink/trunk@171960 bbb929c8-8fbe-4397-9dbb-9b2b20218538