LibWeb/IDB: Implement clear_an_object_store

Author: https://github.com/stelar7
Commit: 637f35c0eb
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4650
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/IndexedDB/Internal/Index.h

@@ -40,6 +40,7 @@ public:
     [[nodiscard]] KeyPath const& key_path() const { return m_key_path; }
 
     [[nodiscard]] bool has_record_with_key(GC::Ref<Key> key);
+    void clear_records();
 
     HTML::SerializationRecord referenced_value(IndexRecord const& index_record) const;