Begin tracking why layout is invalidated

Source/core/layout/LayoutFlowThread.cpp

 /*
  * 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 40 matching lines @@
     m_multiColumnSetList.remove(columnSet);
 }
 
 void LayoutFlowThread::invalidateRegions()
 {
     if (m_regionsInvalidated) {
         ASSERT(selfNeedsLayout());
         return;
     }
 
-    setNeedsLayoutAndFullPaintInvalidation();
+    setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::ColumnsChanged);
 
     m_regionsInvalidated = true;
 }
 
 void LayoutFlowThread::validateRegions()
 {
     if (m_regionsInvalidated) {
         m_regionsInvalidated = false;
         m_regionsHaveUniformLogicalHeight = true;
 
@@ skipping 141 matching lines @@
 
 void LayoutFlowThread::MultiColumnSetSearchAdapter::collectIfNeeded(const MultiColumnSetInterval& interval)
 {
     if (m_result)
         return;
     if (interval.low() <= m_offset && interval.high() > m_offset)
         m_result = interval.data();
 }
 
 } // namespace blink