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/effects/GrCoverageSetOpXP.cpp b/src/gpu/effects/GrCoverageSetOpXP.cpp
index 8e1dbbb..f3f9133 100644
--- a/src/gpu/effects/GrCoverageSetOpXP.cpp
+++ b/src/gpu/effects/GrCoverageSetOpXP.cpp
@@ -211,7 +211,8 @@
         const GrProcessorAnalysisColor&,
         GrProcessorAnalysisCoverage,
         bool hasMixedSamples,
-        const GrCaps& caps) const {
+        const GrCaps& caps,
+        GrClampType) const {
     // We don't support inverting coverage with mixed samples. We don't expect to ever want this in
     // the future, however we could at some point make this work using an inverted coverage
     // modulation table. Note that an inverted table still won't work if there are coverage procs.