DevTools: [Styles] Add -webkit-font-smoothing to the list of inherited properties

Drive-by: fix handling of non-lowercase property names (since CSS is case-agnostic).

R=pfeldman, vsevik
BUG=269116

Review URL: https://chromiumcodereview.appspot.com/22536005

git-svn-id: svn://svn.chromium.org/blink/trunk@155881 bbb929c8-8fbe-4397-9dbb-9b2b20218538