move core of drawPoints into drawDevicePoints

This allows gpu device to share drawPoints functionality, but not include any raster-specific code (i.e. needed raster blitters).

... next: clean up SkPixmap::erase

Bug: skia:14192
Change-Id: I1cc022f3e3c238d778b6f8728c47976a74ff1b92
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/658298
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Florin Malita <fmalita@google.com>
6 files changed