Add support for parsing <grid-line> that includes a 'span'

Source/core/rendering/style/GridPosition.h

 /*
  * Copyright (C) 2012 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 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef GridPosition_h
 #define GridPosition_h
 
 namespace WebCore {
 
 enum GridPositionType {
     AutoPosition,
-    IntegerPosition
+    IntegerPosition,
+    SpanPosition
 };
 
 class GridPosition {
 public:
     GridPosition()
         : m_type(AutoPosition)
         , m_integerPosition(0)
     {
     }
 
     bool isPositive() const { return integerPosition() > 0; }
 
     GridPositionType type() const { return m_type; }
     bool isAuto() const { return m_type == AutoPosition; }
+    bool isInteger() const { return m_type == IntegerPosition; }
+    bool isSpan() const { return m_type == SpanPosition; }
 
     void setIntegerPosition(int position)
     {
         m_type = IntegerPosition;
         m_integerPosition = position;
     }
 
+    // 'span' values cannot be negative, yet we reuse the <integer> position which can
+    // be. This means that we have to convert the span position to an integer, losing
+    // some precision here. It shouldn't be an issue in practice though.
+    void setSpanPosition(int position)
+    {
+        m_type = SpanPosition;
+        m_integerPosition = position;
+    }
+
     int integerPosition() const
     {
         ASSERT(type() == IntegerPosition);
         return m_integerPosition;
     }
 
+    int spanPosition() const
+    {
+        ASSERT(type() == SpanPosition);
+        return m_integerPosition;
+    }
+
     bool operator==(const GridPosition& other) const
     {
         return m_type == other.m_type && m_integerPosition == other.m_integerPosition;
     }
 
 private:
     GridPositionType m_type;
     int m_integerPosition;
 };
 
 } // namespace WebCore
 
 #endif // GridPosition_h