Revert of Temporarily revert just Multiply to see if that's the source of NEON diffs.

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index 28f247bbbad3eacfb05e0884d355dbe281405e8b..2abe55a8ca69ee29bef2ba5297851ab382904c34 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -1493,9 +1493,7 @@
         case SkXfermode::kPlus_Mode:     return SkT4pxXfermode<Plus4f>::Create(rec);
         case SkXfermode::kModulate_Mode: return SkT4pxXfermode<Modulate4f>::Create(rec);
         case SkXfermode::kScreen_Mode:   return SkT4pxXfermode<Screen4f>::Create(rec);
-        // Temporarily reverted to see if this is what's causing NEON diffs.
-        // If not, will try Xor, DstATop, then SrcATop in that order.
-        //case SkXfermode::kMultiply_Mode: return SkT4pxXfermode<Multiply4f>::Create(rec);
+        case SkXfermode::kMultiply_Mode: return SkT4pxXfermode<Multiply4f>::Create(rec);
         default: break;
     }
 #endif