Floats' margins do not collapse with page or column boundaries.

Source/core/layout/LayoutBlockFlow.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003-2013 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
@@ skipping 475 matching lines @@
     void handleAfterSideOfBlock(LayoutBox* lastChild, LayoutUnit top, LayoutUnit bottom, MarginInfo&);
     void setCollapsedBottomMargin(const MarginInfo&);
 
     LayoutUnit applyBeforeBreak(LayoutBox& child, LayoutUnit logicalOffset); // If the child has a before break, then return a new yPos that shifts to the top of the next page/column.
     LayoutUnit applyAfterBreak(LayoutBox& child, LayoutUnit logicalOffset, MarginInfo&); // If the child has an after break, then return a new offset that shifts to the top of the next page/column.
 
     LayoutUnit adjustBlockChildForPagination(LayoutUnit logicalTop, LayoutBox& child, bool atBeforeSideOfBlock);
     // Computes a deltaOffset value that put a line at the top of the next page if it doesn't fit on the current page.
     void adjustLinePositionForPagination(RootInlineBox&, LayoutUnit& deltaOffset);
     // If the child is unsplittable and can't fit on the current page, return the top of the next page/column.
-    LayoutUnit adjustForUnsplittableChild(LayoutBox&, LayoutUnit logicalOffset, bool includeMargins = false);
+    LayoutUnit adjustForUnsplittableChild(LayoutBox&, LayoutUnit logicalOffset);
 
     // Used to store state between styleWillChange and styleDidChange
     static bool s_canPropagateFloatIntoSibling;
 
     LayoutBlockFlowRareData& ensureRareData();
 
     LayoutUnit m_paintInvalidationLogicalTop;
     LayoutUnit m_paintInvalidationLogicalBottom;
 
     bool isSelfCollapsingBlock() const override;
@@ skipping 40 matching lines @@
 
 // END METHODS DEFINED IN LayoutBlockFlowLine
 
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBlockFlow, isLayoutBlockFlow());
 
 } // namespace blink
 
 #endif // LayoutBlockFlow_h