Add shader based blending of kPlus for configs that need clamping

This effectively reverts https://skia-review.googlesource.com/c/skia/+/140500
and relands https://skia-review.googlesource.com/c/skia/+/48183.

Bug: skia:8871
Change-Id: I6b1d5daa3d319e0c078e553926ed9166cca9a24a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/199930
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ops/GrShadowRRectOp.cpp b/src/gpu/ops/GrShadowRRectOp.cpp
index 23545e5..5ee0b37 100644
--- a/src/gpu/ops/GrShadowRRectOp.cpp
+++ b/src/gpu/ops/GrShadowRRectOp.cpp
@@ -255,7 +255,8 @@
 
     FixedFunctionFlags fixedFunctionFlags() const override { return FixedFunctionFlags::kNone; }
 
-    GrProcessorSet::Analysis finalize(const GrCaps&, const GrAppliedClip*, GrFSAAType) override {
+    GrProcessorSet::Analysis finalize(
+            const GrCaps&, const GrAppliedClip*, GrFSAAType, GrClampType) override {
         return GrProcessorSet::EmptySetAnalysis();
     }