[CSS Grid Layout] Support span in auto-placement algorithm

Source/core/rendering/style/GridResolvedPosition.h

Index: Source/core/rendering/style/GridResolvedPosition.h
diff --git a/Source/core/rendering/style/GridResolvedPosition.h b/Source/core/rendering/style/GridResolvedPosition.h
index 7a959cbcce71d566a7bd90a977d020e741515428..e9a79566736cca13b4af8ffbe0dcfb861b01ec7e 100644
--- a/Source/core/rendering/style/GridResolvedPosition.h
+++ b/Source/core/rendering/style/GridResolvedPosition.h
@@ -43,7 +43,8 @@ public:
         return GridResolvedPosition(resolvedPosition);
     }
 
-    static GridSpan resolveGridPositionsFromAutoPlacementPosition(const RenderBox&, GridTrackSizingDirection, const GridResolvedPosition&);
+    static void initialAndFinalPositionsFromStyle(const RenderStyle&, const RenderBox&, GridTrackSizingDirection, GridPosition &initialPosition, GridPosition &finalPosition);
+    static GridSpan resolveGridPositionsFromAutoPlacementPosition(const RenderStyle&, const RenderBox&, GridTrackSizingDirection, const GridResolvedPosition&);
     static PassOwnPtr<GridSpan> resolveGridPositionsFromStyle(const RenderStyle&, const RenderBox&, GridTrackSizingDirection);
     static GridResolvedPosition resolveNamedGridLinePositionFromStyle(const RenderStyle&, const GridPosition&, GridPositionSide);
     static GridResolvedPosition resolveGridPositionFromStyle(const RenderStyle&, const GridPosition&, GridPositionSide);