Add parsing for named grid lines

Source/core/rendering/style/GridPosition.h

Index: Source/core/rendering/style/GridPosition.h
diff --git a/Source/core/rendering/style/GridPosition.h b/Source/core/rendering/style/GridPosition.h
index a099c4fab0d587db1bc3955231007ddaa50dbdda..92bf47625cc860c282db2579061f82bb5fae4992 100644
--- a/Source/core/rendering/style/GridPosition.h
+++ b/Source/core/rendering/style/GridPosition.h
@@ -31,11 +31,13 @@
 #ifndef GridPosition_h
 #define GridPosition_h
 
+#include "wtf/text/WTFString.h"
+
 namespace WebCore {
 
 enum GridPositionType {
     AutoPosition,
-    IntegerPosition,
+    ExplicitPosition, // [ <integer> || <string> ]
     SpanPosition
 };
 
@@ -51,13 +53,14 @@ public:
 
     GridPositionType type() const { return m_type; }
     bool isAuto() const { return m_type == AutoPosition; }
-    bool isInteger() const { return m_type == IntegerPosition; }
+    bool isExplicit() const { return m_type == ExplicitPosition; }
     bool isSpan() const { return m_type == SpanPosition; }
 
-    void setIntegerPosition(int position)
+    void setExplicitPosition(int position, const String& namedGridLine)
     {
-        m_type = IntegerPosition;
+        m_type = ExplicitPosition;
         m_integerPosition = position;
+        m_namedGridLine = namedGridLine;
     }
 
     // 'span' values cannot be negative, yet we reuse the <integer> position which can
@@ -71,10 +74,16 @@ public:
 
     int integerPosition() const
     {
-        ASSERT(type() == IntegerPosition);
+        ASSERT(type() == ExplicitPosition);
         return m_integerPosition;
     }
 
+    String namedGridLine() const
+    {
+        ASSERT(type() == ExplicitPosition);
+        return m_namedGridLine;
+    }
+
     int spanPosition() const
     {
         ASSERT(type() == SpanPosition);
@@ -93,6 +102,7 @@ public:
 private:
     GridPositionType m_type;
     int m_integerPosition;
+    String m_namedGridLine;
 };
 
 } // namespace WebCore