Begin tracking why layout is invalidated

Source/core/layout/LayoutGrid.cpp

 /*
  * Copyright (C) 2011 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1090 matching lines @@
     return style()->isGridAutoFlowDirectionColumn() ? ForRows : ForColumns;
 }
 
 void LayoutGrid::dirtyGrid()
 {
     // Even if this could be redundant, it could be seen as a defensive strategy against
     // style changes events happening during the layout phase or even while the painting process
     // is still ongoing.
     // Forcing a new layout for the Grid render would cancel any ongoing painting and ensure
     // the grid and its children are correctly laid out according to the new style rules.
-    setNeedsLayout();
+    setNeedsLayout(LayoutInvalidationReason::Unknown);

[esprehn, 2015/03/23 20:19:44]

GridChanged ?

 
     m_grid.resize(0);
     m_gridItemCoordinate.clear();
     m_gridIsDirty = true;
     m_gridItemsOverflowingGridArea.resize(0);
     m_gridItemsIndexesMap.clear();
 }
 
 void LayoutGrid::layoutGridItems()
 {
@@ skipping 643 matching lines @@
     if (isFloating())
         return "LayoutGrid (floating)";
     if (isAnonymous())
         return "LayoutGrid (anonymous)";
     if (isRelPositioned())
         return "LayoutGrid (relative positioned)";
     return "LayoutGrid";
 }
 
 } // namespace blink