[CSS Grid] 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 242ca77496414ba6278903db53cd6baeba083fb4..eaee57de5446d472b8e1b9ca2e0dfa0ceeb50298 100644
--- a/Source/core/css/parser/BisonCSSParser-in.cpp
+++ b/Source/core/css/parser/BisonCSSParser-in.cpp
@@ -83,6 +83,7 @@
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/rendering/RenderTheme.h"
+#include "core/rendering/style/GridResolvedPosition.h"
 #include "core/svg/SVGParserUtilities.h"
 #include "platform/FloatConversion.h"
 #include "wtf/BitArray.h"
@@ -4953,18 +4954,18 @@ PassRefPtr<CSSValue> BisonCSSParser::parseGridTemplate()
 
                 // 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 != (unsigned)gridCoordinate.rows.initialPositionIndex + 1)
                     return 0;
 
                 // 2. The new area starts at the same position as the previously parsed area.
-                if (currentCol != gridCoordinate.columns.initialPositionIndex)
+                if (currentCol != (unsigned)gridCoordinate.columns.initialPositionIndex)
                     return 0;
 
                 // 3. The new area ends at the same position as the previously parsed area.
-                if (lookAheadCol != gridCoordinate.columns.finalPositionIndex)
+                if (lookAheadCol != (unsigned)gridCoordinate.columns.finalPositionIndex)
                     return 0;
 
-                ++gridCoordinate.rows.finalPositionIndex;
+                gridCoordinate.rows.finalPositionIndex.setIntegerPosition(gridCoordinate.rows.finalPositionIndex.integerPosition() + 1);
             }
             currentCol = lookAheadCol;
         }