[canvaskit] Use Raster instead of RasterDirect for Canvas2D surface

This also refactors some internal names to be more consistent
with the normal naming convention.

Bug: skia:10717
Change-Id: I69a0d95aaca359e121b3ff84002d0b5f7cadb260
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/334041
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Nathaniel Nifong <nifong@google.com>
5 files changed