[HTML5] EditorRunNative works with GDNative.

This "breaks" our loading bar logic (libraries are not counted).
Fixing it is non trivial and probably deserves investigating a different
strategy.

platform/javascript/os_javascript.h

@@ -87,6 +87,7 @@ public:
 	String get_user_data_dir() const override;
 
 	bool is_userfs_persistent() const override;
+	Error open_dynamic_library(const String p_path, void *&p_library_handle, bool p_also_set_library_path) override;
 
 	void resume_audio();