LibWeb/IDB: Implement IDBCursor::delete

Author: https://github.com/stelar7
Commit: 9c51326fcb
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4720
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/AtkinsSJ ✅
Reviewed-by: https://github.com/shannonbooth

Libraries/LibWeb/IndexedDB/IDBCursor.h

@@ -50,6 +50,7 @@ public:
     WebIDL::ExceptionOr<void> continue_primary_key(JS::Value, JS::Value);
 
     WebIDL::ExceptionOr<GC::Ref<IDBRequest>> update(JS::Value);
+    WebIDL::ExceptionOr<GC::Ref<IDBRequest>> delete_();
 
     [[nodiscard]] JS::Value value() { return m_value.value_or(JS::js_undefined()); }
     [[nodiscard]] GC::Ref<IDBKeyRange> range() { return m_range; }