DW last resort font default name not necessary.

DW last resort font default name not necessary.

Currently in SkFontMgr_DirectWrite when trying to find some last resort
font SystemParametersInfoW failing is considered a fatal error and so
onLegacyCreateTypeface will return nullptr. Instead, treat failure of
getDefaultFontFamily as ignorable and continue to the default default.

BUG=chromium:697672

Change-Id: I1ea018627487fbd39b1d0eebad4c798346d09c94
Reviewed-on: https://skia-review.googlesource.com/9408
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>