Revert "Trigger spell check/remove markers if spell checker gets enabled/disabled."

There were multiple perf regressions. See crbug.com/274569

This reverts commit r156183.

TBR=rouslan@chromium.org

Review URL: https://codereview.chromium.org/23297002

git-svn-id: svn://svn.chromium.org/blink/trunk@156245 bbb929c8-8fbe-4397-9dbb-9b2b20218538