GDScript: Fix conversions from native members accessed by identifier

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

@@ -0,0 +1,11 @@
+class Foo extends Node:
+	func _init():
+		name = 'f'
+		var string: String = name
+		assert(typeof(string) == TYPE_STRING)
+		assert(string == 'f')
+		print('ok')
+
+func test():
+	var foo := Foo.new()
+	foo.free()

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

@@ -0,0 +1,2 @@
+GDTEST_OK
+ok