Revert of Revert of stop calling SkScalarDiv (patchset #1 id:1 of https://codereview.chromium.org/1138263002/)

Reason for revert:
android patched, blink has rolled

Original issue's description:
> Revert of stop calling SkScalarDiv (patchset #4 id:60001 of https://codereview.chromium.org/1135053002/)
>
> Reason for revert:
> need to wait for Blink roll (and patch android)
>
> Original issue's description:
> > stop calling SkScalarDiv
> >
> > BUG=skia:
> > TBR=
> >
> > Committed: https://skia.googlesource.com/skia/+/67d71c898249a7af3523b16c6a69895a63bfae0a
>
> TBR=
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/2629697933b5cc975e45d2a45c48f803fc6cbcec

TBR=
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1135693003
diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index 39bd6c8..b324cc4 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -30,8 +30,8 @@
 
 namespace {
 
-const SkScalar gOneThird = SkScalarInvert(SkIntToScalar(3));
-const SkScalar gTwoThirds = SkScalarDiv(SkIntToScalar(2), SkIntToScalar(3));
+const SkScalar gOneThird = SkIntToScalar(1) / 3;
+const SkScalar gTwoThirds = SkIntToScalar(2) / 3;
 const SkScalar gOneHalf = 0.5f;
 const SkScalar gOneQuarter = 0.25f;