remove unused code around SK_SUPPORT_LEGACY_XFERMODE_PARAM

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4384

Change-Id: I5121acd027d935ade169ff65941f29f654a47bd0
Reviewed-on: https://skia-review.googlesource.com/4384
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/effects/SkLayerDrawLooper.cpp b/src/effects/SkLayerDrawLooper.cpp
index 51a3f77..9337198 100644
--- a/src/effects/SkLayerDrawLooper.cpp
+++ b/src/effects/SkLayerDrawLooper.cpp
@@ -15,7 +15,7 @@
 
 SkLayerDrawLooper::LayerInfo::LayerInfo() {
     fPaintBits = 0;                     // ignore our paint fields
-    fColorMode = (SK_XFERMODE_MODE_PARAM)SkBlendMode::kDst; // ignore our color
+    fColorMode = SkBlendMode::kDst;     // ignore our color
     fOffset.set(0, 0);
     fPostTranslate = false;
 }
@@ -224,7 +224,7 @@
         (void)buffer.readInt();
 
         info.fPaintBits = buffer.readInt();
-        info.fColorMode = (SK_XFERMODE_MODE_PARAM)buffer.readInt();
+        info.fColorMode = (SkBlendMode)buffer.readInt();
         buffer.readPoint(&info.fOffset);
         info.fPostTranslate = buffer.readBool();
         buffer.readPaint(builder.addLayerOnTop(info));