[DirectWrite] Force aliased rendering for Gulim at small sizes

Force full alaiased rendering for the Gulim font as sizes smaller than
12px.

BUG=386400
R=cpu@chromium.org,pdr@chromium.org

Review URL: https://codereview.chromium.org/342853003

git-svn-id: svn://svn.chromium.org/blink/trunk@176527 bbb929c8-8fbe-4397-9dbb-9b2b20218538