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

Source/core/rendering/RenderDeprecatedFlexibleBox.cpp

 /*
  * This file is part of the render object implementation for KHTML.
  *
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 242 matching lines @@
 void RenderDeprecatedFlexibleBox::layoutBlock(bool relayoutChildren)
 {
     ASSERT(needsLayout());
 
     if (!relayoutChildren && simplifiedLayout())
         return;
 
     LayoutRepainter repainter(*this, checkForRepaintDuringLayout());
     LayoutStateMaintainer statePusher(view(), this, locationOffset(), hasTransform() || hasReflection() || style()->isFlippedBlocksWritingMode());
 
-    // Regions changing widths can force us to relayout our children.
-    RenderFlowThread* flowThread = flowThreadContainingBlock();
-    if (logicalWidthChangedInRegions(flowThread))
-        relayoutChildren = true;
-    if (updateRegionsAndShapesLogicalSize(flowThread))
-        relayoutChildren = true;
-
     LayoutSize previousSize = size();
 
     updateLogicalWidth();
     updateLogicalHeight();
 
     if (previousSize != size()
         || (parent()->isDeprecatedFlexibleBox() && parent()->style()->boxOrient() == HORIZONTAL
         && parent()->style()->boxAlign() == BSTRETCH))
         relayoutChildren = true;
 
     setHeight(0);
 
     m_stretchingChildren = false;
 
     if (isHorizontal())
         layoutHorizontalBox(relayoutChildren);
     else
         layoutVerticalBox(relayoutChildren);
 
     LayoutUnit oldClientAfterEdge = clientLogicalBottom();
     updateLogicalHeight();
 
     if (previousSize.height() != height())
         relayoutChildren = true;
 
     layoutPositionedObjects(relayoutChildren || isRoot());
 
-    computeRegionRangeForBlock(flowThread);
-
     computeOverflow(oldClientAfterEdge);
 
     statePusher.pop();
 
     updateLayerTransform();
 
     if (view()->layoutState()->pageLogicalHeight())
         setPageLogicalOffset(view()->layoutState()->pageLogicalOffset(this, logicalTop()));
 
     // Update our scrollbars if we're overflow:auto/scroll/hidden now that we know if
@@ skipping 772 matching lines @@
     if (isPseudoElement())
         return "RenderDeprecatedFlexibleBox (generated)";
     if (isAnonymous())
         return "RenderDeprecatedFlexibleBox (generated)";
     if (isRelPositioned())
         return "RenderDeprecatedFlexibleBox (relative positioned)";
     return "RenderDeprecatedFlexibleBox";
 }
 
 } // namespace WebCore