LibWeb: Properly serialize position/edge style values

Author: https://github.com/Gingeh
Commit: 84150f972f
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2651
Reviewed-by: https://github.com/AtkinsSJ ✅
Reviewed-by: https://github.com/awesomekling

Libraries/LibWeb/CSS/StyleValues/PositionStyleValue.h

@@ -25,8 +25,8 @@ public:
     static ValueComparingNonnullRefPtr<PositionStyleValue> create_center()
     {
         return adopt_ref(*new (nothrow) PositionStyleValue(
-            EdgeStyleValue::create(PositionEdge::Left, Percentage { 50 }),
-            EdgeStyleValue::create(PositionEdge::Top, Percentage { 50 })));
+            EdgeStyleValue::create(PositionEdge::Center, {}),
+            EdgeStyleValue::create(PositionEdge::Center, {})));
     }
     virtual ~PositionStyleValue() override = default;