[New Multicolumn] Correct paint rectangle calculation for compositing.

Source/core/rendering/RenderFlowThread.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 84 matching lines @@
     RenderRegion* lastRegion() const;
 
     virtual bool addForcedRegionBreak(LayoutUnit, RenderObject* breakChild, bool isBefore, LayoutUnit* offsetBreakAdjustment = 0) { return false; }
 
     virtual bool isPageLogicalHeightKnown() const { return true; }
     bool pageLogicalSizeChanged() const { return m_pageLogicalSizeChanged; }
 
     void collectLayerFragments(LayerFragments&, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRect);
     LayoutRect fragmentsBoundingBox(const LayoutRect& layerBoundingBox);
 
+    LayoutPoint flowThreadPointToVisualPoint(const LayoutPoint& flowThreadPoint) const
+    {
+        return flowThreadPoint + columnOffset(flowThreadPoint);
+    }
+
     void pushFlowThreadLayoutState(const RenderObject&);
     void popFlowThreadLayoutState();
     LayoutUnit offsetFromLogicalTopOfFirstRegion(const RenderBlock*) const;
 
     // Used to estimate the maximum height of the flow thread.
     static LayoutUnit maxLogicalHeight() { return LayoutUnit::max() / 2; }
 
 protected:
     virtual const char* renderName() const = 0;
 
@@ skipping 91 matching lines @@
 };
 
 template <> struct ValueToString<RenderMultiColumnSet*> {
     static String string(const RenderMultiColumnSet* value) { return String::format("%p", value); }
 };
 #endif
 
 } // namespace blink
 
 #endif // RenderFlowThread_h