[canvaskit] Remove ReadBuffer

Takes about 20kb off uncompressed size, 8kb gzipped.

Also turns off AAA and DAA on CPU builds (already off on GPU)

Bug: skia:
Change-Id: I708038394b61cc8eb7944d5ad1a3bb494db6c719
Reviewed-on: https://skia-review.googlesource.com/c/165100
Reviewed-by: Mike Klein <mtklein@google.com>
1 file changed