Clean up unflattening paints

Attempting reland after breaking G3
-- fixed by updating layerdrawlooper

Change-Id: I9013baae4ff2acad2040741ba53188d616f2920c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/437679
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/effects/SkLayerDrawLooper.cpp b/src/effects/SkLayerDrawLooper.cpp
index b898c06..63a5639 100644
--- a/src/effects/SkLayerDrawLooper.cpp
+++ b/src/effects/SkLayerDrawLooper.cpp
@@ -231,7 +231,7 @@
         info.fColorMode = (SkBlendMode)buffer.readInt();
         buffer.readPoint(&info.fOffset);
         info.fPostTranslate = buffer.readBool();
-        buffer.readPaint(builder.addLayerOnTop(info), nullptr);
+        *builder.addLayerOnTop(info) = buffer.readPaint();
         if (!buffer.isValid()) {
             return nullptr;
         }