[CSS Grid Layout] Add GridSpan::iterator

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 99 matching lines @@
         ASSERT(resolvedInitialPosition <= resolvedFinalPosition);
     }
 
     bool operator==(const GridSpan& o) const
     {
         return resolvedInitialPosition == o.resolvedInitialPosition && resolvedFinalPosition == o.resolvedFinalPosition;
     }
 
     GridResolvedPosition resolvedInitialPosition;
     GridResolvedPosition resolvedFinalPosition;
+
+    typedef GridResolvedPosition iterator;
+
+    iterator begin() const
+    {
+        return resolvedInitialPosition;
+    }
+
+    iterator end() const
+    {
+        return resolvedFinalPosition.next();
+    }
 };
 
 // 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 16 matching lines @@
 
     GridSpan columns;
     GridSpan rows;
 };
 
 typedef HashMap<String, GridCoordinate> NamedGridAreaMap;
 
 } // namespace WebCore
 
 #endif // GridCoordinate_h