Revert of Add fast normalize for SkLightingImageFilter. (patchset #2 id:20001 of https://codereview.chromium.org/1240023002/)

Reason for revert:
Speculative revert -- DEPS roll block on linux_blink_rel

https://storage.googleapis.com/chromium-layout-test-archives/linux_blink_rel/71483/layout-test-results/results.html

Original issue's description:
> Add fast normalize for SkLightingImageFilter.
>
> The normalize routine in SkPoint3 is very robust. However, for simple
> lighting cases we prefer speed over robustness. This fixes a perf
> regression in smoothness.tough_filters_cases.
>
> BUG=chromium:510562
>
> Committed: https://skia.googlesource.com/skia/+/dfa0ecf169db87f7afddd93bc1c500de481a62c7

TBR=reed@google.com,senorblanco@google.com,senorblanco@chromium.org,jvanverth@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:510562

Review URL: https://codereview.chromium.org/1244523002

1 files changed, 6 insertions, 15 deletions

diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index b82f6ad916..ae49462b5e 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -60,15 +60,6 @@ inline void shiftMatrixLeft(int m[9]) {
     m[7] = m[8];
 }
 
-static inline void fast_normalize(SkPoint3* vector) {
-    // add a tiny bit so we don't have to worry about divide-by-zero
-    SkScalar magSq = vector->dot(*vector) + SK_ScalarNearlyZero;
-    SkScalar scale = sk_float_rsqrt(magSq);
-    vector->fX *= scale;
-    vector->fY *= scale;
-    vector->fZ *= scale;
-}
-
 class DiffuseLightingType {
 public:
     DiffuseLightingType(SkScalar kd)
@@ -99,7 +90,7 @@ public:
                     const SkPoint3& lightColor) const {
         SkPoint3 halfDir(surfaceTolight);
         halfDir.fZ += SK_Scalar1;        // eye position is always (0, 0, 1)
-        fast_normalize(&halfDir);
+        halfDir.normalize();
         SkScalar colorScale = SkScalarMul(fKS,
             SkScalarPow(normal.dot(halfDir), fShininess));
         colorScale = SkScalarClampMax(colorScale, SK_Scalar1);
@@ -122,7 +113,7 @@ inline SkPoint3 pointToNormal(SkScalar x, SkScalar y, SkScalar surfaceScale) {
     SkPoint3 vector = SkPoint3::Make(SkScalarMul(-x, surfaceScale),
                                      SkScalarMul(-y, surfaceScale),
                                      SK_Scalar1);
-    fast_normalize(&vector);
+    vector.normalize();
     return vector;
 }
 
@@ -809,7 +800,7 @@ public:
                                             fLocation.fY - SkIntToScalar(y),
                                             fLocation.fZ - SkScalarMul(SkIntToScalar(z),
                                                                        surfaceScale));
-        fast_normalize(&direction);
+        direction.normalize();
         return direction;
     };
     const SkPoint3& lightColor(const SkPoint3&) const { return this->color(); }
@@ -875,7 +866,7 @@ public:
        fSpecularExponent(SkScalarPin(specularExponent, kSpecularExponentMin, kSpecularExponentMax))
     {
        fS = target - location;
-       fast_normalize(&fS);
+       fS.normalize();
        fCosOuterConeAngle = SkScalarCos(SkDegreesToRadians(cutoffAngle));
        const SkScalar antiAliasThreshold = 0.016f;
        fCosInnerConeAngle = fCosOuterConeAngle + antiAliasThreshold;
@@ -897,7 +888,7 @@ public:
         SkPoint3 target = SkPoint3::Make(target2.fX, target2.fY,
                                          SkScalarAve(targetZ.fX, targetZ.fY));
         SkPoint3 s = target - location;
-        fast_normalize(&s);
+        s.normalize();
         return new SkSpotLight(location,
                                target,
                                fSpecularExponent,
@@ -913,7 +904,7 @@ public:
                                             fLocation.fY - SkIntToScalar(y),
                                             fLocation.fZ - SkScalarMul(SkIntToScalar(z),
                                                                        surfaceScale));
-        fast_normalize(&direction);
+        direction.normalize();
         return direction;
     };
     SkPoint3 lightColor(const SkPoint3& surfaceToLight) const {