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

Source/core/rendering/style/GridCoordinate.h

Index: Source/core/rendering/style/GridCoordinate.h
diff --git a/Source/core/rendering/style/GridCoordinate.h b/Source/core/rendering/style/GridCoordinate.h
index 937d3f08b9b2c73688b0ada58ccf780c3d81b9c1..6c665c1fc3e8f309bfa509ef78c046f9c2b71292 100644
--- a/Source/core/rendering/style/GridCoordinate.h
+++ b/Source/core/rendering/style/GridCoordinate.h
@@ -31,7 +31,7 @@
 #ifndef GridCoordinate_h
 #define GridCoordinate_h
 
-#include "core/rendering/style/GridPosition.h"
+#include "core/rendering/style/GridResolvedPosition.h"
 #include "wtf/HashMap.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/text/WTFString.h"
@@ -42,25 +42,25 @@ namespace WebCore {
 // and |finalPositionIndex| are grid areas' indexes, NOT grid lines'. Iterating over the
 // span should include both |initialPositionIndex| and |finalPositionIndex| to be correct.
 struct GridSpan {
-    static PassOwnPtr<GridSpan> create(size_t initialPosition, size_t finalPosition)
+    static PassOwnPtr<GridSpan> create(const GridResolvedPosition& initialPosition, const GridResolvedPosition& finalPosition)
     {
         return adoptPtr(new GridSpan(initialPosition, finalPosition));
     }
 
-    static PassOwnPtr<GridSpan> createWithSpanAgainstOpposite(size_t resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
+    static PassOwnPtr<GridSpan> createWithSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
     {
         // 'span 1' is contained inside a single grid track regardless of the direction.
         // That's why the CSS span value is one more than the offset we apply.
         size_t positionOffset = position.spanPosition() - 1;
         if (side == ColumnStartSide || side == RowStartSide) {
-            size_t initialResolvedPosition = std::max<int>(0, resolvedOppositePosition - positionOffset);
+            GridResolvedPosition initialResolvedPosition = GridResolvedPosition(std::max<int>(0, resolvedOppositePosition.integerPosition() - positionOffset));
             return GridSpan::create(initialResolvedPosition, resolvedOppositePosition);
         }
 
-        return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition + positionOffset);
+        return GridSpan::create(resolvedOppositePosition, GridResolvedPosition(resolvedOppositePosition.integerPosition() + positionOffset));
     }
 
-    static PassOwnPtr<GridSpan> createWithNamedSpanAgainstOpposite(size_t resolvedOppositePosition, const GridPosition& position, GridPositionSide side, const Vector<size_t>& gridLines)
+    static PassOwnPtr<GridSpan> createWithNamedSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side, const Vector<size_t>& gridLines)
     {
         if (side == RowStartSide || side == ColumnStartSide)
             return createWithInitialNamedSpanAgainstOpposite(resolvedOppositePosition, position, gridLines);
@@ -68,37 +68,38 @@ struct GridSpan {
         return createWithFinalNamedSpanAgainstOpposite(resolvedOppositePosition, position, gridLines);
     }
 
-    static PassOwnPtr<GridSpan> createWithInitialNamedSpanAgainstOpposite(size_t resolvedOppositePosition, const GridPosition& position, const Vector<size_t>& gridLines)
+    static PassOwnPtr<GridSpan> createWithInitialNamedSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, const Vector<size_t>& gridLines)
     {
         // The grid line inequality needs to be strict (which doesn't match the after / end case) because |resolvedOppositePosition|
         // is already converted to an index in our grid representation (ie one was removed from the grid line to account for the side).
         size_t firstLineBeforeOppositePositionIndex = 0;
-        const size_t* firstLineBeforeOppositePosition = std::lower_bound(gridLines.begin(), gridLines.end(), resolvedOppositePosition);
+        const size_t* firstLineBeforeOppositePosition = std::lower_bound(gridLines.begin(), gridLines.end(), resolvedOppositePosition.integerPosition());
         if (firstLineBeforeOppositePosition != gridLines.end())
             firstLineBeforeOppositePositionIndex = firstLineBeforeOppositePosition - gridLines.begin();
 
         size_t gridLineIndex = std::max<int>(0, firstLineBeforeOppositePositionIndex - position.spanPosition() + 1);
         size_t resolvedGridLinePosition = gridLines[gridLineIndex];
-        if (resolvedGridLinePosition > resolvedOppositePosition)
-            resolvedGridLinePosition = resolvedOppositePosition;
-        return GridSpan::create(resolvedGridLinePosition, resolvedOppositePosition);
+        if (resolvedGridLinePosition > resolvedOppositePosition.integerPosition())
+            resolvedGridLinePosition = resolvedOppositePosition.integerPosition();
+        return GridSpan::create(GridResolvedPosition(resolvedGridLinePosition), resolvedOppositePosition);
     }
 
-    static PassOwnPtr<GridSpan> createWithFinalNamedSpanAgainstOpposite(size_t resolvedOppositePosition, const GridPosition& position, const Vector<size_t>& gridLines)
+    static PassOwnPtr<GridSpan> createWithFinalNamedSpanAgainstOpposite(const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, const Vector<size_t>& gridLines)
     {
         size_t firstLineAfterOppositePositionIndex = gridLines.size() - 1;
-        const size_t* firstLineAfterOppositePosition = std::upper_bound(gridLines.begin(), gridLines.end(), resolvedOppositePosition);
+        const size_t* firstLineAfterOppositePosition = std::upper_bound(gridLines.begin(), gridLines.end(), resolvedOppositePosition.integerPosition());
         if (firstLineAfterOppositePosition != gridLines.end())
             firstLineAfterOppositePositionIndex = firstLineAfterOppositePosition - gridLines.begin();
 
         size_t gridLineIndex = std::min(gridLines.size() - 1, firstLineAfterOppositePositionIndex + position.spanPosition() - 1);
-        size_t resolvedGridLinePosition = GridPosition::adjustGridPositionForAfterEndSide(gridLines[gridLineIndex]);
+        size_t resolvedGridLinePositionInteger = GridResolvedPosition::adjustGridPositionForAfterEndSide(gridLines[gridLineIndex]);
+        GridResolvedPosition resolvedGridLinePosition = GridResolvedPosition(resolvedGridLinePositionInteger);
         if (resolvedGridLinePosition < resolvedOppositePosition)
-            resolvedGridLinePosition = resolvedOppositePosition;
+            resolvedGridLinePosition.setIntegerPosition(resolvedOppositePosition.integerPosition());
         return GridSpan::create(resolvedOppositePosition, resolvedGridLinePosition);
     }
 
-    GridSpan(size_t initialPosition, size_t finalPosition)
+    GridSpan(const GridResolvedPosition& initialPosition, const GridResolvedPosition& finalPosition)
         : initialPositionIndex(initialPosition)
         , finalPositionIndex(finalPosition)
     {
@@ -110,8 +111,8 @@ struct GridSpan {
         return initialPositionIndex == o.initialPositionIndex && finalPositionIndex == o.finalPositionIndex;
     }
 
-    size_t initialPositionIndex;
-    size_t finalPositionIndex;
+    GridResolvedPosition initialPositionIndex;
+    GridResolvedPosition finalPositionIndex;
 };
 
 // This represents a grid area that spans in both rows' and columns' direction.