Fix generic font family issue on Android

- standard font family should go Android path on Android;
- for non-generic font families, familyNameFromSettings should return
  an empty AtomicString.

BUG=347121
TEST=platform/android/fast/text/international/non-generic-font-fallback.html
R=dglazkov@chromium.org

Review URL: https://codereview.chromium.org/184703003

git-svn-id: svn://svn.chromium.org/blink/trunk@168173 bbb929c8-8fbe-4397-9dbb-9b2b20218538