LibWeb: Make DOM::Range more suitable for JS.

Author: https://github.com/asynts
Commit: 10f9c85090
Pull-request: https://github.com/SerenityOS/serenity/pull/4318
Reviewed-by: https://github.com/Lubrsi
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/linusg

Libraries/LibWeb/Layout/LayoutPosition.h

@@ -68,7 +68,7 @@ public:
 
     LayoutRange normalized() const;
 
-    DOM::Range to_dom_range() const;
+    NonnullRefPtr<DOM::Range> to_dom_range() const;
 
 private:
     LayoutPosition m_start;