A div can be pan-scrolled beyond its overflow (Windows only)

Source/core/rendering/RenderLayer.h

Index: Source/core/rendering/RenderLayer.h
diff --git a/Source/core/rendering/RenderLayer.h b/Source/core/rendering/RenderLayer.h
index 85053caba376fcfba6e683ea12ac6930530c8342..c59b526cd4656626312e3e278d09c27cd0f24960 100644
--- a/Source/core/rendering/RenderLayer.h
+++ b/Source/core/rendering/RenderLayer.h
@@ -395,7 +395,13 @@ public:
         ScrollOffsetClamped
     };
 
+    enum ScrollPropagation {
+        ShouldPropagateScroll,
+        DontPropagateScroll
+    };
+
     // Scrolling methods for layers that can scroll their overflow.
+    bool scrollBy(const IntSize&, ScrollOffsetClamping = ScrollOffsetUnclamped, ScrollPropagation = DontPropagateScroll);
     void scrollByRecursively(const IntSize&, ScrollOffsetClamping = ScrollOffsetUnclamped);
     void scrollToOffset(const IntSize&, ScrollOffsetClamping = ScrollOffsetUnclamped);
     void scrollToXOffset(int x, ScrollOffsetClamping clamp = ScrollOffsetUnclamped) { scrollToOffset(IntSize(x, scrollYOffset()), clamp); }