Add parsing for named grid lines

Source/core/css/CSSComputedStyleDeclaration.cpp

Index: Source/core/css/CSSComputedStyleDeclaration.cpp
diff --git a/Source/core/css/CSSComputedStyleDeclaration.cpp b/Source/core/css/CSSComputedStyleDeclaration.cpp
index 0841bb95d5e2981c4bf37b473a37e5d235d260b4..dde74996302792c13659d63e3400a36afd42275d 100644
--- a/Source/core/css/CSSComputedStyleDeclaration.cpp
+++ b/Source/core/css/CSSComputedStyleDeclaration.cpp
@@ -1063,12 +1063,15 @@ static PassRefPtr<CSSValue> valueForGridPosition(const GridPosition& position)
     if (position.isAuto())
         return cssValuePool().createIdentifierValue(CSSValueAuto);
 
-    if (position.isInteger())
-        return cssValuePool().createValue(position.integerPosition(), CSSPrimitiveValue::CSS_NUMBER);
-
     RefPtr<CSSValueList> list = CSSValueList::createSpaceSeparated();
-    list->append(cssValuePool().createIdentifierValue(CSSValueSpan));
-    list->append(cssValuePool().createValue(position.spanPosition(), CSSPrimitiveValue::CSS_NUMBER));
+    if (position.isSpan()) {
+        list->append(cssValuePool().createIdentifierValue(CSSValueSpan));
+        list->append(cssValuePool().createValue(position.spanPosition(), CSSPrimitiveValue::CSS_NUMBER));
+    } else {
+        list->append(cssValuePool().createValue(position.integerPosition(), CSSPrimitiveValue::CSS_NUMBER));
+        if (!position.namedGridLine().isNull())
+            list->append(cssValuePool().createValue(position.namedGridLine(), CSSPrimitiveValue::CSS_STRING));
+    }
     return list;
 }
 static PassRefPtr<CSSValue> createTransitionPropertyValue(const CSSAnimationData* animation)