LibWeb: Add HTMLTableCellElement::colSpan

Author: https://github.com/skyrising
Commit: b7b647e9cd
Pull-request: https://github.com/SerenityOS/serenity/pull/13323
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/HTML/HTMLTableCellElement.h

@@ -17,6 +17,9 @@ public:
     HTMLTableCellElement(DOM::Document&, DOM::QualifiedName);
     virtual ~HTMLTableCellElement() override;
 
+    unsigned col_span() const;
+    void set_col_span(unsigned);
+
 private:
     virtual void apply_presentational_hints(CSS::StyleProperties&) const override;
 };