avm1: reference displayObjects parents if parent is a button (#12541)

core/src/display_object/edit_text.rs

@@ -992,7 +992,10 @@ impl<'gc> EditText<'gc> {
             let variable_path = WString::from_utf8(&var_path);
             drop(var_path);
 
-            let parent = self.avm1_parent().unwrap();
+            let mut parent = self.avm1_parent().unwrap();
+            while parent.as_avm1_button().is_some() {
+                parent = parent.avm1_parent().unwrap();
+            }
 
             activation.run_with_child_frame_for_display_object(
                 "[Text Field Binding]",

tests/tests/swfs/visual/text/String_path_variable_button/test.toml

@@ -0,0 +1,8 @@
+num_frames = 1
+
+[image_comparison]
+tolerance = 0
+max_outliers = 12
+
+[player_options]
+with_renderer = { optional = false, sample_count = 1 }