[WHLSL] Implement SampleLevel(), SampleBias(), and SampleGrad()
Created attachment 377815 [details] Patch
Created attachment 377834 [details] Patch
iOS test failure is unrelated.
Comment on attachment 377834 [details] Patch Clearing flags on attachment: 377834 Committed r249453: <https://trac.webkit.org/changeset/249453>
All reviewed patches have been landed. Closing bug.
<rdar://problem/55004295>