remove xfermode flag (again) for g3

BUG=skia:

Change-Id: Ib6842553ff5e8b3003769ac352287dc0e0f7e691
NOTRY=True
Reviewed-on: https://skia-review.googlesource.com/5222
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
1 file changed