Speeup hairline curves (quads and cubics)

/skia/trunk> cat ../old.txt
maxrss	loops	min	median	mean	max	stddev	samples   	config	bench
   9M	1	4.28ms	4.32ms	4.36ms	4.67ms	3%	▄▁▁▃▂▂▁▁▂█	8888	path_hairline_small_AA_cubic
   9M	1	743µs	767µs	770µs	825µs	4%	▃▃▇▃▁▁▅▁█▁	8888	path_hairline_small_AA_conic
   9M	1	533µs	606µs	598µs	680µs	9%	▁▂▂█▆▇▇▄▂▂	8888	path_hairline_small_AA_quad
   9M	1	451µs	452µs	456µs	495µs	3%	▁▁▁▁█▁▁▁▁▁	8888	path_hairline_small_AA_line

/skia/trunk> cat ../new.txt
maxrss	loops	min	median	mean	max	stddev	samples   	config	bench
   9M	1	827µs	827µs	831µs	869µs	2%	▁▁▁▁▁▁▁█▁▁	8888	path_hairline_small_AA_cubic
   9M	1	515µs	517µs	517µs	518µs	0%	▇█▆▅▃▃▁▁▁▅	8888	path_hairline_small_AA_conic
   9M	1	310µs	311µs	315µs	332µs	2%	▂▁█▆▁▁▁▁▁▁	8888	path_hairline_small_AA_quad
   9M	1	254µs	254µs	258µs	276µs	3%	▁▁▁▁▁▁▁█▇▂	8888	path_hairline_small_AA_line

Edited revert of https://codereview.chromium.org/1085013003

TBR=

Review URL: https://codereview.chromium.org/1078413003

1 files changed, 8 insertions, 2 deletions

diff --git a/src/core/SkBlitter.h b/src/core/SkBlitter.h
index 2d4a0defbf..8d9f7bcbed 100644
--- a/src/core/SkBlitter.h
+++ b/src/core/SkBlitter.h
@@ -8,6 +8,12 @@
 #ifndef SkBlitter_DEFINED
 #define SkBlitter_DEFINED
 
+#ifdef SK_SUPPORT_LEGACY_BLITANTIH2V2
+    #define SK_BLITANTIH2V2_VIRTUAL
+#else
+    #define SK_BLITANTIH2V2_VIRTUAL virtual
+#endif
+
 #include "SkBitmap.h"
 #include "SkBitmapProcShader.h"
 #include "SkMask.h"
@@ -54,7 +60,7 @@ public:
     virtual const SkBitmap* justAnOpaqueColor(uint32_t* value);
 
     // (x, y), (x + 1, y)
-    void blitAntiH2(int x, int y, U8CPU a0, U8CPU a1) {
+    SK_BLITANTIH2V2_VIRTUAL void blitAntiH2(int x, int y, U8CPU a0, U8CPU a1) {
         int16_t runs[3];
         uint8_t aa[2];
         
@@ -67,7 +73,7 @@ public:
     }
 
     // (x, y), (x, y + 1)
-    void blitAntiV2(int x, int y, U8CPU a0, U8CPU a1) {
+    SK_BLITANTIH2V2_VIRTUAL void blitAntiV2(int x, int y, U8CPU a0, U8CPU a1) {
         int16_t runs[2];
         uint8_t aa[1];