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

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 377 matching lines @@
     int scrollWidth() const;
     int scrollHeight() const;
 
     void panScrollFromPoint(const IntPoint&);
 
     enum ScrollOffsetClamping {
         ScrollOffsetUnclamped,
         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); }
     void scrollToYOffset(int y, ScrollOffsetClamping clamp = ScrollOffsetUnclamped) { scrollToOffset(IntSize(scrollXOffset(), y), clamp); }
 
     int scrollXOffset() const { return m_scrollOffset.width() + scrollOrigin().x(); }
     int scrollYOffset() const { return m_scrollOffset.height() + scrollOrigin().y(); }
     IntSize adjustedScrollOffset() const { return IntSize(scrollXOffset(), scrollYOffset()); }
 
     void scrollRectToVisible(const LayoutRect&, const ScrollAlignment& alignX, const ScrollAlignment& alignY);
@@ skipping 908 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h