Revert of Update feSpotLight to match spec (patchset #2 id:20001 of https://codereview.chromium.org/1403403003/ )

Reason for revert:
re-land once layout test have been disabled (so they can be rebased)

Original issue's description:
> Update feSpotLight to match spec
>
> This change updates feSpotLight to match the spec via two changes:
>
> 1) specularExponent is ignored if the spotlight has no coneAngle (GPU
>    bug only). This change updates the GPU path so that it matches the
>    CPU path and the spec in this regard.
>
> 2) specularExponent is clamped to the 1-128 range. The spec does not
>    specify a clamp for the specularExponent attribute of feSpotLight.
>    Note that the spec *does* specify this clamp for the
>    specularExponent attribute of feSpecularLighting. It looks like we
>    incorrectly applied this to both specularExponent attributes.
>
>    This change (along with a parallel change in Blink) allows us to pass
>    the SVG filter effects conformance test here:
>    http://www.w3.org/Graphics/SVG/Test/20110816/harness/htmlObject/filters-light-01-f.html
>
>    Additionally, this brings our behavior in line with Safari and Edge’s
>    behavior on this filter.
>
> Two new cases were added to gm/lighting.cpp to catch these issues:
> - The existing spotlight case exercised the path where our specular
>   exponent was between 1-128 and had a limiting cone angle.
> - The first new spotlight case exercises the path where our specular
>   exponent is between 1-128 and we do not have a limiting cone angle.
> - The second new spotlight case exercises the path where the specular
>   exponent is not within the 1-128 range, to ensure that we don’t
>   incorrectly clip to this range.
>
> BUG=472849
>
> Committed: https://skia.googlesource.com/skia/+/c84ccb070258db2803a9e8f532bfe7239a737063

TBR=senorblanco@google.com,senorblanco@chromium.org,bsalomon@google.com,ericrk@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=472849

Review URL: https://codereview.chromium.org/1417463006
diff --git a/gm/lighting.cpp b/gm/lighting.cpp
index 0ce9599..af102d7 100644
--- a/gm/lighting.cpp
+++ b/gm/lighting.cpp
@@ -10,7 +10,7 @@
 #include "SkOffsetImageFilter.h"
 #include "SkPoint3.h"
 
-#define WIDTH 550
+#define WIDTH 330
 #define HEIGHT 660
 
 namespace skiagm {
@@ -69,10 +69,8 @@
                                                SkIntToScalar(-10),
                                                SkIntToScalar(20));
         SkPoint3 spotTarget = SkPoint3::Make(SkIntToScalar(40), SkIntToScalar(40), 0);
-        SkScalar spotExponent1 = SK_Scalar1;
-        SkScalar spotExponent0 = SkIntToScalar(0);
-        SkScalar cutoffAngleSmall = SkIntToScalar(15);
-        SkScalar cutoffAngleNone = SkIntToScalar(180);
+        SkScalar spotExponent = SK_Scalar1;
+        SkScalar cutoffAngle = SkIntToScalar(15);
         SkScalar kd = SkIntToScalar(2);
         SkScalar ks = SkIntToScalar(1);
         SkScalar shininess = SkIntToScalar(8);
@@ -106,8 +104,8 @@
 
             paint.setImageFilter(SkLightingImageFilter::CreateSpotLitDiffuse(spotLocation,
                                                                              spotTarget,
-                                                                             spotExponent1,
-                                                                             cutoffAngleSmall,
+                                                                             spotExponent,
+                                                                             cutoffAngle,
                                                                              white,
                                                                              surfaceScale,
                                                                              kd,
@@ -115,28 +113,6 @@
                                                                              cr))->unref();
             drawClippedBitmap(canvas, paint, 220, y);
 
-            paint.setImageFilter(SkLightingImageFilter::CreateSpotLitDiffuse(spotLocation,
-                                                                             spotTarget,
-                                                                             spotExponent1,
-                                                                             cutoffAngleNone,
-                                                                             white,
-                                                                             surfaceScale,
-                                                                             kd,
-                                                                             input,
-                                                                             cr))->unref();
-            drawClippedBitmap(canvas, paint, 330, y);
-
-            paint.setImageFilter(SkLightingImageFilter::CreateSpotLitDiffuse(spotLocation,
-                                                                             spotTarget,
-                                                                             spotExponent0,
-                                                                             cutoffAngleNone,
-                                                                             white,
-                                                                             surfaceScale,
-                                                                             kd,
-                                                                             input,
-                                                                             cr))->unref();
-            drawClippedBitmap(canvas, paint, 440, y);
-
             y += 110;
 
             paint.setImageFilter(SkLightingImageFilter::CreatePointLitSpecular(pointLocation,
@@ -159,8 +135,8 @@
 
             paint.setImageFilter(SkLightingImageFilter::CreateSpotLitSpecular(spotLocation,
                                                                               spotTarget,
-                                                                              spotExponent1,
-                                                                              cutoffAngleSmall,
+                                                                              spotExponent,
+                                                                              cutoffAngle,
                                                                               white,
                                                                               surfaceScale,
                                                                               ks,
@@ -169,30 +145,6 @@
                                                                               cr))->unref();
             drawClippedBitmap(canvas, paint, 220, y);
 
-            paint.setImageFilter(SkLightingImageFilter::CreateSpotLitSpecular(spotLocation,
-                                                                              spotTarget,
-                                                                              spotExponent1,
-                                                                              cutoffAngleNone,
-                                                                              white,
-                                                                              surfaceScale,
-                                                                              ks,
-                                                                              shininess,
-                                                                              input,
-                                                                              cr))->unref();
-            drawClippedBitmap(canvas, paint, 330, y);
-
-            paint.setImageFilter(SkLightingImageFilter::CreateSpotLitSpecular(spotLocation,
-                                                                              spotTarget,
-                                                                              spotExponent0,
-                                                                              cutoffAngleNone,
-                                                                              white,
-                                                                              surfaceScale,
-                                                                              ks,
-                                                                              shininess,
-                                                                              input,
-                                                                              cr))->unref();
-            drawClippedBitmap(canvas, paint, 440, y);
-
             y += 110;
         }
     }