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/src/effects/SkImageSource.cpp b/src/effects/SkImageSource.cpp
index f434de4..f96a4a1 100644
--- a/src/effects/SkImageSource.cpp
+++ b/src/effects/SkImageSource.cpp
@@ -108,7 +108,7 @@
 
     // Subtract off the integer component of the translation (will be applied in offset, below).
     dstRect.offset(-SkIntToScalar(dstIRect.fLeft), -SkIntToScalar(dstIRect.fTop));
-    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
+    paint.setBlendMode(SkBlendMode::kSrc);
     // FIXME: this probably shouldn't be necessary, but drawImageRect asserts
     // None filtering when it's translate-only
     paint.setFilterQuality(