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

Source/core/css/CSSGridTemplateAreasValue.cpp

Index: Source/core/css/CSSGridTemplateAreasValue.cpp
diff --git a/Source/core/css/CSSGridTemplateAreasValue.cpp b/Source/core/css/CSSGridTemplateAreasValue.cpp
index d27c5b6955fd4ce4d20af5196973efe18059dc9d..73d50e352720ed60623dae6aa6fd049a7da66dc4 100644
--- a/Source/core/css/CSSGridTemplateAreasValue.cpp
+++ b/Source/core/css/CSSGridTemplateAreasValue.cpp
@@ -52,14 +52,14 @@ static String stringForPosition(const NamedGridAreaMap& gridAreaMap, size_t row,
     NamedGridAreaMap::const_iterator end = gridAreaMap.end();
     for (NamedGridAreaMap::const_iterator it = gridAreaMap.begin(); it != end; ++it) {
         const GridCoordinate& coordinate = it->value;
-        if (row >= coordinate.rows.initialPositionIndex && row <= coordinate.rows.finalPositionIndex)
+        if (row >= coordinate.rows.initialPositionIndex.integerPosition() && row <= coordinate.rows.finalPositionIndex.integerPosition())
             candidates.append(it->key);
     }
 
     end = gridAreaMap.end();
     for (NamedGridAreaMap::const_iterator it = gridAreaMap.begin(); it != end; ++it) {
         const GridCoordinate& coordinate = it->value;
-        if (column >= coordinate.columns.initialPositionIndex && column <= coordinate.columns.finalPositionIndex && candidates.contains(it->key))
+        if (column >= coordinate.columns.initialPositionIndex.integerPosition() && column <= coordinate.columns.finalPositionIndex.integerPosition() && candidates.contains(it->key))
             return it->key;
     }