LibWeb/IDB: Implement count_the_records_in_a_range

Author: https://github.com/stelar7
Commit: 694375d3ac
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4505
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/IndexedDB/Internal/ObjectStore.h

@@ -52,6 +52,7 @@ public:
     void remove_records_in_range(GC::Ref<IDBKeyRange> range);
     bool has_record_with_key(GC::Ref<Key> key);
     void store_a_record(Record const& record);
+    u64 count_records_in_range(GC::Ref<IDBKeyRange> range);
 
 protected:
     virtual void visit_edges(Visitor&) override;