LibWeb: Add support for range deletion.

Author: https://github.com/asynts
Commit: 43dc47a494
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

@@ -68,6 +68,8 @@ public:
 
     LayoutRange normalized() const;
 
+    DOM::Range to_dom_range() const;
+
 private:
     LayoutPosition m_start;
     LayoutPosition m_end;