*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/rendering/RenderReplica.cpp

 /*
  * Copyright (C) 2008 Apple Inc. 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 66 matching lines @@
 
     if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseMask)
         return;
 
     LayoutPoint adjustedPaintOffset = paintOffset + location();
 
     if (paintInfo.phase == PaintPhaseForeground) {
         // Turn around and paint the parent layer. Use temporary clipRects, so that the layer doesn't end up caching clip rects
         // computing using the wrong rootLayer
         RenderLayer* rootPaintingLayer = layer()->transform() ? layer()->parent() : layer()->enclosingTransformedAncestor();
-        LayerPaintingInfo paintingInfo(rootPaintingLayer, paintInfo.rect, PaintBehaviorNormal, LayoutSize(), 0, paintInfo.renderRegion);
+        LayerPaintingInfo paintingInfo(rootPaintingLayer, paintInfo.rect, PaintBehaviorNormal, LayoutSize(), 0);
         PaintLayerFlags flags = PaintLayerHaveTransparency | PaintLayerAppliedTransform | PaintLayerTemporaryClipRects | PaintLayerPaintingReflection;
         layer()->parent()->paintLayer(paintInfo.context, paintingInfo, flags);
     } else if (paintInfo.phase == PaintPhaseMask)
         paintMask(paintInfo, adjustedPaintOffset);
 }
 
 } // namespace WebCore