Revert "Revert "SkTypes: extract SkTo""

This reverts commit fdcfb8b7c23fbf18f872d2c31d27978235033876.

> Original change's description:
> > SkTypes: extract SkTo
> >
> > Change-Id: I8de790d5013db2105ad885fa2683303d7c250b09
> > Reviewed-on: https://skia-review.googlesource.com/133620
> > Reviewed-by: Mike Klein <mtklein@google.com>

Change-Id: Ida74fbc5c21248a724a5edbf9fae18a33bcb23aa
Reviewed-on: https://skia-review.googlesource.com/134506
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index d80ceee..e38d736 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -5,7 +5,8 @@
  * found in the LICENSE file.
  */
 
-#include <cmath>
+#include "SkPath.h"
+
 #include "SkBuffer.h"
 #include "SkCubicClipper.h"
 #include "SkData.h"
@@ -18,6 +19,9 @@
 #include "SkPointPriv.h"
 #include "SkRRect.h"
 #include "SkSafeMath.h"
+#include "SkTo.h"
+
+#include <cmath>
 
 static float poly_eval(float A, float B, float C, float t) {
     return (A * t + B) * t + C;