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/tests/ImageTest.cpp b/tests/ImageTest.cpp
index 993c3fa..74dd532 100644
--- a/tests/ImageTest.cpp
+++ b/tests/ImageTest.cpp
@@ -351,7 +351,7 @@
     }
 
     SkPaint paint;
-    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
+    paint.setBlendMode(SkBlendMode::kSrc);
     paint.setColor(SK_ColorRED);
 
     surface->getCanvas()->drawRect(SkRect::MakeXYWH(1, 1, 1, 1), paint);