Revert "Revert "speed up A8 by creating a new entry-point in SkDraw that blits the path's coverage …

src/core/SkCoreBlitters.h

Index: src/core/SkCoreBlitters.h
diff --git a/src/core/SkCoreBlitters.h b/src/core/SkCoreBlitters.h
index 9455509c483de68684056f4f8ed035bbff54c4fe..673b8745456061f85e37dfafcb05b0d4e68c73dc 100644
--- a/src/core/SkCoreBlitters.h
+++ b/src/core/SkCoreBlitters.h
@@ -40,6 +40,17 @@ private:
 
 ///////////////////////////////////////////////////////////////////////////////
 
+class SkA8_Coverage_Blitter : public SkRasterBlitter {
+public:
+    SkA8_Coverage_Blitter(const SkBitmap& device, const SkPaint& paint);
+    virtual void blitH(int x, int y, int width) SK_OVERRIDE;
+    virtual void blitAntiH(int x, int y, const SkAlpha antialias[], const int16_t runs[]) SK_OVERRIDE;
+    virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE;
+    virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE;
+    virtual void blitMask(const SkMask&, const SkIRect&) SK_OVERRIDE;
+    virtual const SkBitmap* justAnOpaqueColor(uint32_t*) SK_OVERRIDE;
+};
+
 class SkA8_Blitter : public SkRasterBlitter {
 public:
     SkA8_Blitter(const SkBitmap& device, const SkPaint& paint);