[CSS Grid Layout] Support span in auto-placement algorithm

Source/core/rendering/style/GridCoordinate.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 96 matching lines @@
         , finalPositionIndex(finalPosition)
     {
         ASSERT(initialPositionIndex <= finalPositionIndex);
     }
 
     bool operator==(const GridSpan& o) const
     {
         return initialPositionIndex == o.initialPositionIndex && finalPositionIndex == o.finalPositionIndex;
     }
 
+    size_t spanningPositions() const

[Julien - ping for review, 2014/04/04 00:10:16]

This name is also confusing for me. I would rather to name it integerSpan (or
just "span" even if that would be ambiguous).

+    {
+        return finalPositionIndex - initialPositionIndex + 1;
+    }
+
     size_t initialPositionIndex;
     size_t finalPositionIndex;
 };
 
 // This represents a grid area that spans in both rows' and columns' direction.
 struct GridCoordinate {
     // HashMap requires a default constuctor.
     GridCoordinate()
         : columns(0, 0)
         , rows(0, 0)
@@ skipping 18 matching lines @@
 
     GridSpan columns;
     GridSpan rows;
 };
 
 typedef HashMap<String, GridCoordinate> NamedGridAreaMap;
 
 } // namespace WebCore
 
 #endif // GridCoordinate_h