LibWeb: Implement HTMLTableRowElement.deleteCell

Author: https://github.com/Lubrsi
Commit: 009f04fa46
Pull-request: https://github.com/SerenityOS/serenity/pull/15964
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.h

@@ -20,6 +20,8 @@ public:
 
     int row_index() const;
     int section_row_index() const;
+    WebIDL::ExceptionOr<JS::NonnullGCPtr<HTMLTableCellElement>> insert_cell(i32 index);
+    WebIDL::ExceptionOr<void> delete_cell(i32 index);
 
 private:
     HTMLTableRowElement(DOM::Document&, DOM::QualifiedName);