[CSS Grid Layout] Add GridSpan::iterator

Source/core/rendering/style/GridResolvedPosition.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef GridResolvedPosition_h
 #define GridResolvedPosition_h
 
 #include "core/rendering/style/GridPosition.h"
 
 namespace WebCore {
@@ skipping 56 matching lines @@
     {
         m_integerPosition++;
         return *this;
     }
 
     bool operator==(const GridResolvedPosition& other) const
     {
         return m_integerPosition == other.m_integerPosition;
     }
 
+    bool operator!=(const GridResolvedPosition& other) const
+    {
+        return m_integerPosition != other.m_integerPosition;
+    }
+
     bool operator<(const GridResolvedPosition& other) const
     {
         return m_integerPosition < other.m_integerPosition;
     }
 
     bool operator>(const GridResolvedPosition& other) const
     {
         return m_integerPosition > other.m_integerPosition;
     }
 
     bool operator<=(const GridResolvedPosition& other) const
     {
         return m_integerPosition <= other.m_integerPosition;
     }
 
     bool operator>=(const GridResolvedPosition& other) const
     {
         return m_integerPosition >= other.m_integerPosition;
     }
 
     size_t toInt() const
     {
         return m_integerPosition;
     }
 
+    GridResolvedPosition next() const
+    {
+        return GridResolvedPosition(m_integerPosition + 1);
+    }
+
     static size_t explicitGridColumnCount(const RenderStyle&);
     static size_t explicitGridRowCount(const RenderStyle&);
 
 private:
 
     static size_t explicitGridSizeForSide(const RenderStyle&, GridPositionSide);
 
     size_t m_integerPosition;
 };
 
 } // namespace WebCore
 
 #endif // GridResolvedPosition_h