[css-grid] Implement grid gutters

third_party/WebKit/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 54 matching lines @@
         ASSERT(!m_gridIsDirty);
         return m_columnPositions;
     }
 
     const Vector<LayoutUnit>& rowPositions() const
     {
         ASSERT(!m_gridIsDirty);
         return m_rowPositions;
     }
 
+    LayoutUnit guttersSize(GridTrackSizingDirection, size_t span) const;
+
     typedef Vector<LayoutBox*, 1> GridCell;
     const GridCell& gridCell(int row, int column) const
     {
         ASSERT_WITH_SECURITY_IMPLICATION(!m_gridIsDirty);
         return m_grid[row][column];
     }
 
     const Vector<LayoutBox*>& itemsOverflowingGridArea() const
     {
         ASSERT_WITH_SECURITY_IMPLICATION(!m_gridIsDirty);
@@ skipping 117 matching lines @@
     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