Begin tracking why layout is invalidated

Source/core/layout/LayoutFrameSet.cpp

 /**
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  *           (C) 2000 Stefan Schimanski (1Stein@gmx.de)
  * Copyright (C) 2004, 2005, 2006 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 403 matching lines @@
     for (int r = 0; r < rows; r++) {
         position.setX(0);
         size.setHeight(m_rows.m_sizes[r]);
         for (int c = 0; c < cols; c++) {
             child->setLocation(position);
             size.setWidth(m_cols.m_sizes[c]);
 
             // has to be resized and itself resize its contents
             if (size != child->size()) {
                 child->setSize(size);
-                child->setNeedsLayoutAndFullPaintInvalidation();
+                child->setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::SizeChanged);
                 child->layout();
             }
 
             position.setX(position.x() + size.width() + borderThickness);
 
             child = child->nextSiblingBox();
             if (!child)
                 return;
         }
         position.setY(position.y() + size.height() + borderThickness);
@@ skipping 19 matching lines @@
     if (needsLayout())
         return;
     if (axis.m_splitBeingResized == noSplit)
         return;
     int currentSplitPosition = splitPosition(axis, axis.m_splitBeingResized);
     int delta = (position - currentSplitPosition) - axis.m_splitResizeOffset;
     if (!delta)
         return;
     axis.m_deltas[axis.m_splitBeingResized - 1] += delta;
     axis.m_deltas[axis.m_splitBeingResized] -= delta;
-    setNeedsLayoutAndFullPaintInvalidation();
+    setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::SizeChanged);
 }
 
 bool LayoutFrameSet::userResize(MouseEvent* evt)
 {
     if (!m_isResizing) {
         if (needsLayout())
             return false;
         if (evt->type() == EventTypeNames::mousedown && evt->button() == LeftButton) {
             FloatPoint localPos = absoluteToLocal(FloatPoint(evt->absoluteLocation()), UseTransforms);
             startResizing(m_cols, localPos.x());
@@ skipping 93 matching lines @@
         return SetCursor;
     }
     if (canResizeColumn(roundedPoint)) {
         cursor = columnResizeCursor();
         return SetCursor;
     }
     return LayoutBox::getCursor(point, cursor);
 }
 
 } // namespace blink