MediaWiki Theme: Remove text-shadow on  button
MediaWiki Theme: Remove text-shadow on  button

Design spec at https://trello.com/c/bRZ9C6Ho/1-primary-buttons

Change-Id: I856d020be226727cf6c0fea9a27eea33fb3f8d92

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui