DevTools: Add UA presets for Opera 12 on Win/Mac

Patch from Mathias Bynens <mathiasb@opera.com>
BUG=336383

Review URL: https://codereview.chromium.org/143893003

git-svn-id: svn://svn.chromium.org/blink/trunk@165655 bbb929c8-8fbe-4397-9dbb-9b2b20218538