Add default virtual gdscript:// path to GDScript instances

modules/gdscript/tests/scripts/runtime/features/gdscript.gd

@@ -0,0 +1,20 @@
+func test():
+	var gdscr: = GDScript.new()
+	gdscr.source_code = '''
+extends Resource
+
+func test() -> void:
+	prints("Outer")
+	var inner = InnerClass.new()
+
+class InnerClass:
+	func _init() -> void:
+		prints("Inner")
+'''
+	@warning_ignore(return_value_discarded)
+	gdscr.reload()
+
+	var inst = gdscr.new()
+
+	@warning_ignore(unsafe_method_access)
+	inst.test()

modules/gdscript/tests/scripts/runtime/features/gdscript.out

@@ -0,0 +1,3 @@
+GDTEST_OK
+Outer
+Inner