[CSS Grid] Introduce an explicit type for resolved grid positions

Source/core/rendering/RenderGrid.h

Index: Source/core/rendering/RenderGrid.h
diff --git a/Source/core/rendering/RenderGrid.h b/Source/core/rendering/RenderGrid.h
index f8a4de326f5ae0a01cd81ae68c2f2f3ae9e743e1..515047aae1b623d3be0068c86c5024b9b445ff14 100644
--- a/Source/core/rendering/RenderGrid.h
+++ b/Source/core/rendering/RenderGrid.h
@@ -28,6 +28,7 @@
 
 #include "core/rendering/OrderIterator.h"
 #include "core/rendering/RenderBlock.h"
+#include "core/rendering/style/GridResolvedPosition.h"
 
 namespace WebCore {
 
@@ -117,12 +118,10 @@ private:
 
     GridSpan resolveGridPositionsFromAutoPlacementPosition(const RenderBox*, GridTrackSizingDirection, size_t) const;
     PassOwnPtr<GridSpan> resolveGridPositionsFromStyle(const RenderBox*, GridTrackSizingDirection) const;
-    size_t resolveNamedGridLinePositionFromStyle(const GridPosition&, GridPositionSide) const;
-    size_t resolveGridPositionFromStyle(const GridPosition&, GridPositionSide) const;
-    PassOwnPtr<GridSpan> resolveGridPositionAgainstOppositePosition(size_t resolvedOppositePosition, const GridPosition&, GridPositionSide) const;
-    PassOwnPtr<GridSpan> resolveNamedGridLinePositionAgainstOppositePosition(size_t resolvedOppositePosition, const GridPosition&, GridPositionSide) const;
-    PassOwnPtr<GridSpan> resolveBeforeStartNamedGridLinePositionAgainstOppositePosition(size_t resolvedOppositePosition, const GridPosition&, const Vector<size_t>&) const;
-    PassOwnPtr<GridSpan> resolveAfterEndNamedGridLinePositionAgainstOppositePosition(size_t resolvedOppositePosition, const GridPosition&, const Vector<size_t>&) const;
+    GridResolvedPosition resolveNamedGridLinePositionFromStyle(const GridPosition&, GridPositionSide) const;
+    GridResolvedPosition resolveGridPositionFromStyle(const GridPosition&, GridPositionSide) const;
+    PassOwnPtr<GridSpan> resolveGridPositionAgainstOppositePosition(const GridResolvedPosition& resolvedOppositePosition, const GridPosition&, GridPositionSide) const;
+    PassOwnPtr<GridSpan> resolveNamedGridLinePositionAgainstOppositePosition(const GridResolvedPosition& resolvedOppositePosition, const GridPosition&, GridPositionSide) const;
 
     LayoutUnit gridAreaBreadthForChild(const RenderBox* child, GridTrackSizingDirection, const Vector<GridTrack>&) const;