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

Source/core/rendering/style/GridPosition.h

Index: Source/core/rendering/style/GridPosition.h
diff --git a/Source/core/rendering/style/GridPosition.h b/Source/core/rendering/style/GridPosition.h
index 133cdd55123c08b56221f0043f193da859e1d8ac..256f4163dbbcccdc33ca4a6278369f7ed5477b15 100644
--- a/Source/core/rendering/style/GridPosition.h
+++ b/Source/core/rendering/style/GridPosition.h
@@ -42,13 +42,6 @@ enum GridPositionType {
     NamedGridAreaPosition // <ident>
 };
 
-enum GridPositionSide {
-    ColumnStartSide,
-    ColumnEndSide,
-    RowStartSide,
-    RowEndSide
-};
-
 class GridPosition {
 public:
     GridPosition()
@@ -57,20 +50,6 @@ public:
     {
     }
 
-    static size_t adjustGridPositionForAfterEndSide(size_t resolvedPosition)
-    {
-        return resolvedPosition ? resolvedPosition - 1 : 0;
-    }
-
-    static size_t adjustGridPositionForSide(size_t resolvedPosition, GridPositionSide side)
-    {
-        // An item finishing on the N-th line belongs to the N-1-th cell.
-        if (side == ColumnEndSide || side == RowEndSide)
-            return adjustGridPositionForAfterEndSide(resolvedPosition);
-
-        return resolvedPosition;
-    }
-
     bool isPositive() const { return integerPosition() > 0; }
 
     GridPositionType type() const { return m_type; }