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/tests/BlurTest.cpp b/tests/BlurTest.cpp
index 4e9a246..4ecc934 100644
--- a/tests/BlurTest.cpp
+++ b/tests/BlurTest.cpp
@@ -454,7 +454,7 @@
     SkLayerDrawLooper::LayerInfo info;
 
     info.fPaintBits = 0;
-    info.fColorMode = (SK_XFERMODE_MODE_PARAM)SkBlendMode::kDst;
+    info.fColorMode = SkBlendMode::kDst;
     builder->addLayer(info);
 }
 
@@ -462,7 +462,7 @@
     SkLayerDrawLooper::LayerInfo info;
 
     info.fPaintBits = SkLayerDrawLooper::kMaskFilter_Bit;
-    info.fColorMode = (SK_XFERMODE_MODE_PARAM)SkBlendMode::kSrc;
+    info.fColorMode = SkBlendMode::kSrc;
     SkPaint* paint = builder->addLayer(info);
     paint->setMaskFilter(std::move(mf));
 }