sksl SPIR-V sampledBuffer support

Bug: skia:
Change-Id: I9bf936857b61d3bb5a165f7a11e53d25069b53c2
Reviewed-on: https://skia-review.googlesource.com/15192
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
4 files changed