Revert[8] "replace SkXfermode obj with SkBlendMode enum in paints"

This reverts commit c245574ba3d0e2ade6c94b2812de3baa383bf4c4.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2396953002

TBR=

Review-Url: https://codereview.chromium.org/2396953002
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 0565ee9..585a51d 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -1454,7 +1454,7 @@
     SkCanvas canvas(uprighted);
     canvas.concat(upright);
     SkPaint paint;
-    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
+    paint.setBlendMode(SkBlendMode::kSrc);
     canvas.drawBitmap(*bitmap, 0, 0, &paint);
 
     *bitmap = uprighted;