Unify some SkNx code

src/effects/gradients/SkLinearGradient.cpp

Index: src/effects/gradients/SkLinearGradient.cpp
diff --git a/src/effects/gradients/SkLinearGradient.cpp b/src/effects/gradients/SkLinearGradient.cpp
index 53264e4d8cf014e384d97eb20577c61addd4fc8c..8760029795fa2af063f2aa0c10838d315db1ed5b 100644
--- a/src/effects/gradients/SkLinearGradient.cpp
+++ b/src/effects/gradients/SkLinearGradient.cpp
@@ -150,7 +150,7 @@ SkLinearGradient::LinearGradientContext::LinearGradientContext(
         const Sk4f scale(1, 1, 1, paintAlpha);
         for (int i = 0; i < count; ++i) {
             uint32_t c = SkSwizzle_Color_to_PMColor(shader.fOrigColors[i]);
-            rec[i].fColor = Sk4f::FromBytes((const uint8_t*)&c) * scale;
+            rec[i].fColor = SkNx_cast<float>(Sk4b::Load((const uint8_t*)&c)) * scale;
             if (i > 0) {
                 SkASSERT(rec[i - 1].fPos <= rec[i].fPos);
             }
@@ -162,7 +162,7 @@ SkLinearGradient::LinearGradientContext::LinearGradientContext(
         for (int i = 0; i < count; ++i) {
             SkPMColor pmc = SkPreMultiplyColor(shader.fOrigColors[i]);
             pmc = SkAlphaMulQ(pmc, alphaScale);
-            rec[i].fColor = Sk4f::FromBytes((const uint8_t*)&pmc);
+            rec[i].fColor = SkNx_cast<float>(Sk4b::Load((const uint8_t*)&pmc));
             if (i > 0) {
                 SkASSERT(rec[i - 1].fPos <= rec[i].fPos);
             }
@@ -699,7 +699,7 @@ find_backward(const SkLinearGradient::LinearGradientContext::Rec rec[], float ti
 
 template <bool apply_alpha> SkPMColor trunc_from_255(const Sk4f& x) {
     SkPMColor c;
-    x.toBytes((uint8_t*)&c);
+    SkNx_cast<uint8_t>(x).store((uint8_t*)&c);
     if (apply_alpha) {
         c = SkPreMultiplyARGB(SkGetPackedA32(c), SkGetPackedR32(c),
                               SkGetPackedG32(c), SkGetPackedB32(c));
@@ -751,7 +751,7 @@ template <bool apply_alpha> void ramp(SkPMColor dstC[], int n, const Sk4f& c, co
     Sk4f cd3 = cd1 + dc2;
     while (n >= 4) {
         if (!apply_alpha) {
-            Sk4f::ToBytes((uint8_t*)dstC, cd0, cd1, cd2, cd3);
+            Sk4f_ToBytes((uint8_t*)dstC, cd0, cd1, cd2, cd3);
             dstC += 4;
         } else {
             *dstC++ = trunc_from_255<apply_alpha>(cd0);