Switch to using accessibilityEnabled and inlineTextBoxAccessibilityEnabled from settings

Depends on https://codereview.chromium.org/497263002/

BUG=406622

Review URL: https://codereview.chromium.org/495763005

git-svn-id: svn://svn.chromium.org/blink/trunk@181120 bbb929c8-8fbe-4397-9dbb-9b2b20218538