Remove a bunch of dead code from RenderLayer

sky/engine/core/rendering/RenderLayerScrollableArea.cpp

Index: sky/engine/core/rendering/RenderLayerScrollableArea.cpp
diff --git a/sky/engine/core/rendering/RenderLayerScrollableArea.cpp b/sky/engine/core/rendering/RenderLayerScrollableArea.cpp
index cc7273cf342e5e145ee301181cd487d07f6dc66d..f076a41983ca12821d085d3ea3f371cacabaaca9 100644
--- a/sky/engine/core/rendering/RenderLayerScrollableArea.cpp
+++ b/sky/engine/core/rendering/RenderLayerScrollableArea.cpp
@@ -733,13 +733,7 @@ void RenderLayerScrollableArea::paintOverflowControls(GraphicsContext* context,
         if (!overflowControlsIntersectRect(localDamgeRect))
             return;
 
-        RenderView* renderView = box().view();
-
-        RenderLayer* paintingRoot = layer()->enclosingLayerWithCompositedLayerMapping(IncludeSelf);
-        if (!paintingRoot)
-            paintingRoot = renderView->layer();
-
-        paintingRoot->setContainsDirtyOverlayScrollbars(true);
+        box().view()->layer()->setContainsDirtyOverlayScrollbars(true);
         return;
     }