Revert of Revert of stop calling SkScalarDiv

src/effects/SkDisplacementMapEffect.cpp

Index: src/effects/SkDisplacementMapEffect.cpp
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index 6f0911ce68381d519226fc5dd512a64ba0bcc75e..2b9665c2c8eb4bd76b71d70f7bdbf42ef1c52f8e 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -56,7 +56,7 @@
                          SkBitmap* src,
                          const SkIRect& bounds)
 {
-    static const SkScalar Inv8bit = SkScalarDiv(SK_Scalar1, 255.0f);
+    static const SkScalar Inv8bit = SkScalarInvert(255);
     const int srcW = src->width();
     const int srcH = src->height();
     const SkVector scaleForColor = SkVector::Make(SkScalarMul(scale.fX, Inv8bit),
@@ -625,8 +625,8 @@
                                         const GrProcessor& proc) {
     const GrDisplacementMapEffect& displacementMap = proc.cast<GrDisplacementMapEffect>();
     GrTexture* colorTex = displacementMap.texture(1);
-    SkScalar scaleX = SkScalarDiv(displacementMap.scale().fX, SkIntToScalar(colorTex->width()));
-    SkScalar scaleY = SkScalarDiv(displacementMap.scale().fY, SkIntToScalar(colorTex->height()));
+    SkScalar scaleX = displacementMap.scale().fX / colorTex->width();
+    SkScalar scaleY = displacementMap.scale().fY / colorTex->height();
     pdman.set2f(fScaleUni, SkScalarToFloat(scaleX),
                 colorTex->origin() == kTopLeft_GrSurfaceOrigin ?
                 SkScalarToFloat(scaleY) : SkScalarToFloat(-scaleY));