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/tests/GrMeshTest.cpp b/tests/GrMeshTest.cpp
index aa951c0..3417a7e 100644
--- a/tests/GrMeshTest.cpp
+++ b/tests/GrMeshTest.cpp
@@ -275,8 +275,7 @@
 
     const char* name() const override { return "GrMeshTestOp"; }
     FixedFunctionFlags fixedFunctionFlags() const override { return FixedFunctionFlags::kNone; }
-    RequiresDstTexture finalize(const GrCaps&, const GrAppliedClip*,
-                                GrPixelConfigIsClamped) override {
+    RequiresDstTexture finalize(const GrCaps&, const GrAppliedClip*) override {
         return RequiresDstTexture::kNo;
     }
     bool onCombineIfPossible(GrOp* other, const GrCaps& caps) override { return false; }