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

Source/core/css/parser/CSSPropertyParser.cpp

Index: Source/core/css/parser/CSSPropertyParser.cpp
diff --git a/Source/core/css/parser/CSSPropertyParser.cpp b/Source/core/css/parser/CSSPropertyParser.cpp
index 2581a1f4f28f0a73b6e78d071e29bd84386a2798..61c16043b184c3cbad703b06930ca5b98d1a41a5 100644
--- a/Source/core/css/parser/CSSPropertyParser.cpp
+++ b/Source/core/css/parser/CSSPropertyParser.cpp
@@ -3710,18 +3710,18 @@ PassRefPtrWillBeRawPtr<CSSValue> CSSPropertyParser::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.resolvedInitialPosition.next())
                     return nullptr;
 
                 // 2. The new area starts at the same position as the previously parsed area.
-                if (currentCol != gridCoordinate.columns.initialPositionIndex)
+                if (currentCol != gridCoordinate.columns.resolvedInitialPosition)
                     return nullptr;
 
                 // 3. The new area ends at the same position as the previously parsed area.
-                if (lookAheadCol != gridCoordinate.columns.finalPositionIndex)
+                if (lookAheadCol != gridCoordinate.columns.resolvedFinalPosition)
                     return nullptr;
 
-                ++gridCoordinate.rows.finalPositionIndex;
+                ++gridCoordinate.rows.resolvedFinalPosition;
             }
             currentCol = lookAheadCol;
         }