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

Source/WebCore/css/CSSComputedStyleDeclaration.cpp

Index: Source/WebCore/css/CSSComputedStyleDeclaration.cpp
diff --git a/Source/WebCore/css/CSSComputedStyleDeclaration.cpp b/Source/WebCore/css/CSSComputedStyleDeclaration.cpp
index 5a4be66d108de6ab0db6e6fccbd9c175321b3fa2..b420e8ee3df595a861ee1560a306ab943d6db5f5 100644
--- a/Source/WebCore/css/CSSComputedStyleDeclaration.cpp
+++ b/Source/WebCore/css/CSSComputedStyleDeclaration.cpp
@@ -1054,7 +1054,13 @@ static PassRefPtr<CSSValue> valueForGridPosition(const GridPosition& position)
     if (position.isAuto())
         return cssValuePool().createIdentifierValue(CSSValueAuto);
 
-    return cssValuePool().createValue(position.integerPosition(), CSSPrimitiveValue::CSS_NUMBER);
+    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));
+    return list;
 }
 static PassRefPtr<CSSValue> createTransitionPropertyValue(const Animation* animation)
 {