remove more references to draw filter

TBR=bungeman@google.com
NOTRY=true
Docs-Preview: https://skia.org/?cl=140798
Bug: skia:6818
Change-Id: Ia741238f65b55cf20b6f4a813a573e84d29a2dfd
Reviewed-on: https://skia-review.googlesource.com/140798
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
6 files changed