Remove clamping of kPlus with F16 configs

The most common use-case for F16 is to draw things that are explicitly
outside of [0,1]. We can't prevent out-of-range values in general, users
could just draw out-of-range content in src mode. We've decided that
it's best to avoid surprising behavior, and trust the user in these
situations.

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

Bug: skia:
Change-Id: I71c2dd925c567e2862d96ab70c752f19245a69c4
Reviewed-on: https://skia-review.googlesource.com/140500
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/src/gpu/ops/GrRegionOp.cpp b/src/gpu/ops/GrRegionOp.cpp
index cd51152..852cd46 100644
--- a/src/gpu/ops/GrRegionOp.cpp
+++ b/src/gpu/ops/GrRegionOp.cpp
@@ -102,10 +102,9 @@
 
     FixedFunctionFlags fixedFunctionFlags() const override { return fHelper.fixedFunctionFlags(); }
 
-    RequiresDstTexture finalize(const GrCaps& caps, const GrAppliedClip* clip,
-                                GrPixelConfigIsClamped dstIsClamped) override {
-        return fHelper.xpRequiresDstTexture(caps, clip, dstIsClamped,
-                                            GrProcessorAnalysisCoverage::kNone, &fRegions[0].fColor);
+    RequiresDstTexture finalize(const GrCaps& caps, const GrAppliedClip* clip) override {
+        return fHelper.xpRequiresDstTexture(caps, clip, GrProcessorAnalysisCoverage::kNone,
+                                            &fRegions[0].fColor);
     }
 
 private: