Add Sk4f::ToBytes(uint8_t[16], Sk4f, Sk4f, Sk4f, Sk4f)

bench/Sk4fBench.cpp

Index: bench/Sk4fBench.cpp
diff --git a/bench/Sk4fBench.cpp b/bench/Sk4fBench.cpp
index 02ac14591d6bc9a7b32d74cb206daa3a0d34ca1b..b2f2b4a58efcc5bd8726e8f4e91f60daa84dac79 100644
--- a/bench/Sk4fBench.cpp
+++ b/bench/Sk4fBench.cpp
@@ -62,10 +62,7 @@ struct Sk4fGradientBench : public Benchmark {
                  c = b + dcdx,
                  d = c + dcdx;
             for (size_t i = 0; i < SK_ARRAY_COUNT(fDevice); i += 4) {
-                a.toBytes((uint8_t*)(fDevice+i+0));
-                b.toBytes((uint8_t*)(fDevice+i+1));
-                c.toBytes((uint8_t*)(fDevice+i+2));
-                d.toBytes((uint8_t*)(fDevice+i+3));
+                Sk4f::ToBytes((uint8_t*)(fDevice+i), a, b, c, d);
                 a = a + dcdx4;
                 b = b + dcdx4;
                 c = c + dcdx4;