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

Source/core/css/parser/BisonCSSParser-in.cpp

Index: Source/core/css/parser/BisonCSSParser-in.cpp
diff --git a/Source/core/css/parser/BisonCSSParser-in.cpp b/Source/core/css/parser/BisonCSSParser-in.cpp
index 14dca1bc0f6e95e5c2c68a8da7d89ae49095df21..0e1f9839a7a67a1ff16e7ed81cd4ed9ae0bd8cc0 100644
--- a/Source/core/css/parser/BisonCSSParser-in.cpp
+++ b/Source/core/css/parser/BisonCSSParser-in.cpp
@@ -4916,18 +4916,18 @@ PassRefPtr<CSSValue> BisonCSSParser::parseGridTemplateAreas()
 
                 // The following checks test that the grid area is a single filled-in rectangle.
                 // 1. The new row is adjacent to the previously parsed row.
-                if (rowCount != gridCoordinate.rows.initialPositionIndex + 1)
+                if (rowCount != gridCoordinate.rows.initialPositionIndex.integerPosition() + 1)
                     return 0;
 
                 // 2. The new area starts at the same position as the previously parsed area.
-                if (currentCol != gridCoordinate.columns.initialPositionIndex)
+                if (currentCol != gridCoordinate.columns.initialPositionIndex.integerPosition())
                     return 0;
 
                 // 3. The new area ends at the same position as the previously parsed area.
-                if (lookAheadCol != gridCoordinate.columns.finalPositionIndex)
+                if (lookAheadCol != gridCoordinate.columns.finalPositionIndex.integerPosition())
                     return 0;
 
-                ++gridCoordinate.rows.finalPositionIndex;
+                gridCoordinate.rows.finalPositionIndex.setIntegerPosition(gridCoordinate.rows.finalPositionIndex.integerPosition() + 1);
             }
             currentCol = lookAheadCol;
         }