Auto-compare GrProcessors' texture accesses in isEqual().

R=joshualitt@google.com

Review URL: https://codereview.chromium.org/654313002
diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index 0e063d9..24bfbbd 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -1304,8 +1304,7 @@
 
 bool GrLightingEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
     const GrLightingEffect& s = sBase.cast<GrLightingEffect>();
-    return this->texture(0) == s.texture(0) &&
-           fLight->isEqual(*s.fLight) &&
+    return fLight->isEqual(*s.fLight) &&
            fSurfaceScale == s.fSurfaceScale;
 }