Revert "Add SkRuntimeBlender class."

This reverts commit 6034941cc28a28a7c9fc79d6cb815fed188cdfb6.

Reason for revert: breaking MSVC build 

Original change's description:
> Add SkRuntimeBlender class.
>
> This class is returned by SkRuntimeEffect::makeBlender when a runtime
> blend is returned. SkRuntimeBlendBuilder is also added as a convenience
> class to simplify creation and uniform setup.
>
> Our ability to add tests is limited in this CL because the SkPaint does
> not contain an SkBlender yet. We do have one test which builds an
> SkBlender, but there's not much we can do with it. Testing will be
> bulked up in the next CL.
>
> Change-Id: Ib2d7d04186690ec0d2238fc990a19d9e6b786ce3
> Bug: skia:12080
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/417006
> Commit-Queue: John Stiles <johnstiles@google.com>
> Auto-Submit: John Stiles <johnstiles@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

TBR=brianosman@google.com,johnstiles@google.com

Change-Id: Id916f7458b827cbfdbc951c8f02aed16e2f44935
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:12080
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/419159
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
3 files changed