Fix typefacesMatchesFamily to treat family string as UTF8

Fix bug in FontCacheSkiaWin::typefacesMatchesFamily where the family
name returned by skia was converted to cstring without setting the
encoding to UTF8.

This was caught by fast/text/backslash-to-yen-sign-euc.html and is
only applicable if the GDI code path is disabled.

BUG=249099
R=bungeman@google.com

Review URL: https://chromiumcodereview.appspot.com/23549036

git-svn-id: svn://svn.chromium.org/blink/trunk@157985 bbb929c8-8fbe-4397-9dbb-9b2b20218538