Strengthen the LayoutGrid dirtiness asserts.

Source/core/layout/LayoutGrid.h

 /*
  * 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 17 matching lines @@
 
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/OrderIterator.h"
 #include "core/style/GridResolvedPosition.h"
 
 namespace blink {
 
 struct GridCoordinate;
 struct GridSpan;
 class GridTrack;
-class GridItemWithSpan;
 
 class LayoutGrid final : public LayoutBlock {
 public:
-    LayoutGrid(Element*);
+    explicit LayoutGrid(Element*);
     virtual ~LayoutGrid();
 
     virtual const char* name() const override { return "LayoutGrid"; }
 
     virtual void layoutBlock(bool relayoutChildren) override;
 
     virtual bool canCollapseAnonymousBlockChild() const override { return false; }
 
     void dirtyGrid();
 
-    const Vector<LayoutUnit>& columnPositions() const { return m_columnPositions; }
-    const Vector<LayoutUnit>& rowPositions() const { return m_rowPositions; }
+    const Vector<LayoutUnit>& columnPositions() const
+    {
+        ASSERT(!m_gridIsDirty);
+        return m_columnPositions;
+    }
+
+    const Vector<LayoutUnit>& rowPositions() const
+    {
+        ASSERT(!m_gridIsDirty);
+        return m_rowPositions;
+    }
 
     typedef Vector<LayoutBox*, 1> GridCell;
-    const GridCell& gridCell(int row, int column) { return m_grid[row][column]; }
-    const Vector<LayoutBox*>& itemsOverflowingGridArea() { return m_gridItemsOverflowingGridArea; }
-    int paintIndexForGridItem(const LayoutBox* layoutBox) { return m_gridItemsIndexesMap.get(layoutBox); }
+    const GridCell& gridCell(int row, int column)
+    {
+        ASSERT_WITH_SECURITY_IMPLICATION(!m_gridIsDirty);
+        return m_grid[row][column];
+    }
 
-    bool gridIsDirty() const { return m_gridIsDirty; }
+    const Vector<LayoutBox*>& itemsOverflowingGridArea()
+    {
+        ASSERT_WITH_SECURITY_IMPLICATION(!m_gridIsDirty);
+        return m_gridItemsOverflowingGridArea;
+    }
 
+    int paintIndexForGridItem(const LayoutBox* layoutBox)
+    {
+        ASSERT_WITH_SECURITY_IMPLICATION(!m_gridIsDirty);
+        return m_gridItemsIndexesMap.get(layoutBox);
+    }
+
+private:
     typedef void (GridTrack::* AccumulatorGrowFunction)(LayoutUnit);
-private:
+
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutGrid || LayoutBlock::isOfType(type); }
     virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const override;
     virtual void computePreferredLogicalWidths() override;
 
     virtual void addChild(LayoutObject* newChild, LayoutObject* beforeChild = 0) override;
     virtual void removeChild(LayoutObject*) override;
 
     virtual void styleDidChange(StyleDifference, const ComputedStyle*) override;
 
     bool explicitGridDidResize(const ComputedStyle&) const;
@@ skipping 69 matching lines @@
 
 #if ENABLE(ASSERT)
     bool tracksAreWiderThanMinTrackBreadth(GridTrackSizingDirection, const Vector<GridTrack>&);
 #endif
 
     size_t gridItemSpan(const LayoutBox&, GridTrackSizingDirection);
     bool spanningItemCrossesFlexibleSizedTracks(const GridCoordinate&, GridTrackSizingDirection) const;
 
     size_t gridColumnCount() const
     {
-        ASSERT(!gridIsDirty());
+        ASSERT(!m_gridIsDirty);
         return m_grid[0].size();
     }
     size_t gridRowCount() const
     {
-        ASSERT(!gridIsDirty());
+        ASSERT(!m_gridIsDirty);
         return m_grid.size();
     }
 
     bool hasDefiniteLogicalSize(GridTrackSizingDirection) const;
 
     typedef Vector<Vector<GridCell>> GridRepresentation;
     GridRepresentation m_grid;
     bool m_gridIsDirty;
     Vector<LayoutUnit> m_rowPositions;
     Vector<LayoutUnit> m_columnPositions;
     HashMap<const LayoutBox*, GridCoordinate> m_gridItemCoordinate;
     OrderIterator m_orderIterator;
     Vector<LayoutBox*> m_gridItemsOverflowingGridArea;
     HashMap<const LayoutBox*, size_t> m_gridItemsIndexesMap;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutGrid, isLayoutGrid());
 
 } // namespace blink
 
 #endif // LayoutGrid_h