Merge FontPlatformDataSkia with FontPlatformData

FontPlatformDataSkia is now compiled on all platforms. Merge it with
FontPlatformData.

BUG=286450
R=pdr@chromium.org

Review URL: https://codereview.chromium.org/622883002

git-svn-id: svn://svn.chromium.org/blink/trunk@183169 bbb929c8-8fbe-4397-9dbb-9b2b20218538