core: Ignore non-tabbable objects from tab ordering

These objects include:
* invisible objects along with their children,
* non-editable text fields.

The method `is_tab_enabled` is renamed to `is_tabbable`, as it no
longer represents the `tabEnabled` property value, but also
incorporates other logic.

core/src/display_object.rs

@@ -1915,7 +1915,7 @@ pub trait TDisplayObject<'gc>:
     }
 
     /// Whether this object is included in tab ordering.
-    fn is_tab_enabled(&self, _context: &mut UpdateContext<'_, 'gc>) -> bool {
+    fn is_tabbable(&self, _context: &mut UpdateContext<'_, 'gc>) -> bool {
         false
     }
 

core/src/display_object/avm1_button.rs

@@ -422,7 +422,7 @@ impl<'gc> TDisplayObject<'gc> for Avm1Button<'gc> {
         self.call_focus_handler(context, focused, other);
     }
 
-    fn is_tab_enabled(&self, context: &mut UpdateContext<'_, 'gc>) -> bool {
+    fn is_tabbable(&self, context: &mut UpdateContext<'_, 'gc>) -> bool {
         self.get_avm1_boolean_property(context, "tabEnabled", |_| true)
     }
 

core/src/display_object/container.rs

@@ -489,7 +489,11 @@ pub trait TDisplayObjectContainer<'gc>:
         }
 
         for child in self.iter_render_list() {
-            if child.is_tab_enabled(context) {
+            if !child.visible() {
+                // Non-visible objects and their children are excluded from tab ordering.
+                continue;
+            }
+            if child.is_tabbable(context) {
                 tab_order.push(child);
             }
             if let Some(container) = child.as_container() {

core/src/display_object/edit_text.rs

@@ -2347,7 +2347,12 @@ impl<'gc> TDisplayObject<'gc> for EditText<'gc> {
         true
     }
 
-    fn is_tab_enabled(&self, context: &mut UpdateContext<'_, 'gc>) -> bool {
+    fn is_tabbable(&self, context: &mut UpdateContext<'_, 'gc>) -> bool {
+        if !self.is_editable() {
+            // Non-editable text fields are never tabbable.
+            return false;
+        }
+
         self.get_avm1_boolean_property(context, "tabEnabled", |_| true)
     }
 

core/src/display_object/movie_clip.rs

@@ -3031,7 +3031,7 @@ impl<'gc> TDisplayObject<'gc> for MovieClip<'gc> {
         self.call_focus_handler(context, focused, other);
     }
 
-    fn is_tab_enabled(&self, context: &mut UpdateContext<'_, 'gc>) -> bool {
+    fn is_tabbable(&self, context: &mut UpdateContext<'_, 'gc>) -> bool {
         self.get_avm1_boolean_property(context, "tabEnabled", |context| {
             self.tab_index().is_some() || self.is_button_mode(context)
         })