add SK_USE_OLD_255_TO_256 define to disable alpha+1 change to SkAlpha255To256
git-svn-id: http://skia.googlecode.com/svn/trunk@171 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/core/SkColorPriv.h b/include/core/SkColorPriv.h
index a82697e..7658d5b 100644
--- a/include/core/SkColorPriv.h
+++ b/include/core/SkColorPriv.h
@@ -33,7 +33,7 @@
*/
static inline unsigned SkAlpha255To256(U8CPU alpha) {
SkASSERT(SkToU8(alpha) == alpha);
-#if 1
+#ifndef SK_USE_OLD_255_TO_256
// this one assues that blending on top of an opaque dst keeps it that way
// even though it is less accurate than a+(a>>7) for non-opaque dsts
return alpha + 1;