Unify some SkNx code

bench/Sk4fBench.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Benchmark.h"
 #include "SkColor.h"
 #include "SkNx.h"
@@ skipping 15 matching lines @@
     const char* onGetName() override { return "Sk4f_roundtrip"; }
     bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
 
     void onDraw(int loops, SkCanvas* canvas) override {
         // Unlike blackhole, junk can and probably will be a register.
         uint32_t junk = 0;
         uint32_t seed = 0;
         for (int i = 0; i < loops; i++) {
             uint32_t color = lcg_rand(&seed),
                      back;
-            auto f = Sk4f::FromBytes((const uint8_t*)&color);
-            f.toBytes((uint8_t*)&back);
+            auto f = SkNx_cast<float>(Sk4b::Load((const uint8_t*)&color));
+            SkNx_cast<uint8_t>(f).store((uint8_t*)&back);
             junk ^= back;
         }
         blackhole ^= junk;
     }
 };
 DEF_BENCH(return new Sk4fBytesRoundtripBench;)
 
 struct Sk4fGradientBench : public Benchmark {
     const char* onGetName() override { return "Sk4f_gradient"; }
     bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
 
     SkPMColor fDevice[100];
     void onDraw(int loops, SkCanvas*) override {
         Sk4f c0(0,0,255,255),
              c1(255,0,0,255),
              dc = c1 - c0,
              fx(0.1f),
              dx(0.002f),
              dcdx(dc*dx),
              dcdx4(dcdx+dcdx+dcdx+dcdx);
 
         for (int n = 0; n < loops; n++) {
             Sk4f a = c0 + dc*fx + Sk4f(0.5f),  // add an extra 0.5f to get rounding for free.
                  b = a + dcdx,
                  c = b + dcdx,
                  d = c + dcdx;
             for (size_t i = 0; i < SK_ARRAY_COUNT(fDevice); i += 4) {
-                Sk4f::ToBytes((uint8_t*)(fDevice+i), a, b, c, d);
+                Sk4f_ToBytes((uint8_t*)(fDevice+i), a, b, c, d);
                 a = a + dcdx4;
                 b = b + dcdx4;
                 c = c + dcdx4;
                 d = d + dcdx4;
             }
         }
     }
 };
 DEF_BENCH(return new Sk4fGradientBench;)