Refactor Sk2x<T> + Sk4x<T> into SkNf<N,T> and SkNi<N,T>

tests/PMFloatTest.cpp

Index: tests/PMFloatTest.cpp
diff --git a/tests/PMFloatTest.cpp b/tests/PMFloatTest.cpp
index 309cd60f4ac8537dfec35624b3004312a4821251..435969c21f27107b4156e0afa84ab1fad983b43d 100644
--- a/tests/PMFloatTest.cpp
+++ b/tests/PMFloatTest.cpp
@@ -32,9 +32,9 @@ DEF_TEST(SkPMFloat, r) {
     REPORTER_ASSERT(r, SkScalarNearlyEqual(  1.0f, clamped.g()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual(  0.0f, clamped.b()));
 
-    // Test SkPMFloat <-> Sk4f conversion.
-    Sk4f fs = clamped;
-    SkPMFloat scaled = fs * Sk4f(0.25f);
+    // Test SkPMFloat <-> Sk4s conversion.
+    Sk4s fs = clamped;
+    SkPMFloat scaled = fs * Sk4s(0.25f);
     REPORTER_ASSERT(r, SkScalarNearlyEqual(63.75f, scaled.a()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual(38.25f, scaled.r()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual( 0.25f, scaled.g()));