GDScript: partially allow some functions on invalid scripts

+ always default initialize static variables
+ dont invalidate script when dependant scripts don't compile/resolve

modules/gdscript/gdscript.h

@@ -169,9 +169,7 @@ private:
 	GDScriptFunction *static_initializer = nullptr;
 
 	Error _static_init();
-#ifdef TOOLS_ENABLED
 	void _static_default_init(); // Initialize static variables with default values based on their types.
-#endif
 
 	int subclass_count = 0;
 	RBSet<Object *> instances;