collectLayerFragments() expects a dirty rect relative to the multicol container.

Source/core/layout/LayoutFlowThread.h

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 80 matching lines @@
     LayoutUnit pageRemainingLogicalHeightForOffset(LayoutUnit, PageBoundaryRule = IncludePageBoundary);
 
     virtual void setPageBreak(LayoutUnit /*offset*/, LayoutUnit /*spaceShortage*/) { }
     virtual void updateMinimumPageHeight(LayoutUnit /*offset*/, LayoutUnit /*minHeight*/) { }
 
     virtual bool addForcedColumnBreak(LayoutUnit, LayoutObject* breakChild, bool isBefore, LayoutUnit* offsetBreakAdjustment = nullptr) { return false; }
 
     virtual bool isPageLogicalHeightKnown() const { return true; }
     bool pageLogicalSizeChanged() const { return m_pageLogicalSizeChanged; }
 
-    void collectLayerFragments(DeprecatedPaintLayerFragments&, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRect);
+    void collectLayerFragments(DeprecatedPaintLayerFragments&, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRectInFlowThread);
 
     // Return the visual bounding box based on the supplied flow-thread bounding box. Both
     // rectangles are completely physical in terms of writing mode.
     LayoutRect fragmentsBoundingBox(const LayoutRect& layerBoundingBox) const;
 
     LayoutPoint flowThreadPointToVisualPoint(const LayoutPoint& flowThreadPoint) const
     {
         return flowThreadPoint + columnOffset(flowThreadPoint);
     }
 
@@ skipping 45 matching lines @@
 };
 
 template <> struct ValueToString<LayoutMultiColumnSet*> {
     static String string(const LayoutMultiColumnSet* value) { return String::format("%p", value); }
 };
 #endif
 
 } // namespace blink
 
 #endif // LayoutFlowThread_h