DevTools: [Styles] Fix "Show inherited" checkbox vertical alignment

This was a regression from r163448

R=aandrey, eustas, vsevik
BUG=331289
NOTRY=true

Review URL: https://codereview.chromium.org/131493003

git-svn-id: svn://svn.chromium.org/blink/trunk@164855 bbb929c8-8fbe-4397-9dbb-9b2b20218538