Optimize color xforms with 2.2 gammas for SSE2

src/core/SkColorSpaceXform.h

Index: src/core/SkColorSpaceXform.h
diff --git a/src/core/SkColorSpaceXform.h b/src/core/SkColorSpaceXform.h
index d54d1b812d2885a674078ba3ab3468107481ffd8..34726435199ddf10905cb6dae3ad65fed114e870 100644
--- a/src/core/SkColorSpaceXform.h
+++ b/src/core/SkColorSpaceXform.h
@@ -34,17 +34,15 @@ public:
     virtual ~SkColorSpaceXform() {}
 };
 
-class SkGammaByValueXform : public SkColorSpaceXform {
+class Sk2Dot2Xform : public SkColorSpaceXform {
 public:
 
     void xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const override;
 
 private:
-    SkGammaByValueXform(float srcGammas[3], const SkMatrix44& srcToDst, float dstGammas[3]);
+    Sk2Dot2Xform(const SkMatrix44& srcToDst);
 
-    float            fSrcGammas[3];
-    const SkMatrix44 fSrcToDst;
-    float            fDstGammas[3];
+    float fSrcToDst[16];
 
     friend class SkColorSpaceXform;
 };