ObjectTypeDB was renamed to ClassDB. Types are meant to be more generic to Variant.

All usages of "type" to refer to classes were renamed to "class"
ClassDB has been exposed to GDScript.
OBJ_TYPE() macro is now GDCLASS()

core/io/xml_parser.h

@@ -40,7 +40,7 @@
 
 class XMLParser : public Reference {
 
-	OBJ_TYPE( XMLParser, Reference );
+	GDCLASS( XMLParser, Reference );
 public:
 	//! Enumeration of all supported source text file formats
 	enum SourceFormat {