Convert fast/multicol/columns-shorthand-parsing to reftest.

 * Use standards mode.
 * Adjust test slightly to make ref easier to make.

R=mstensho@opera.com
BUG=386567

Review URL: https://codereview.chromium.org/655253004

git-svn-id: svn://svn.chromium.org/blink/trunk@184222 bbb929c8-8fbe-4397-9dbb-9b2b20218538