avm1: Get child clip instances in StageObject

Add the logic to get children display objects as properties in
`StageObject`.

core/src/avm1/object.rs

@@ -48,23 +48,7 @@ pub trait TObject<'gc>: 'gc + Collect + Debug + Into<Object<'gc>> + Clone + Copy
         if self.has_own_property(name) {
             self.get_local(name, avm, context, (*self).into())
         } else {
-            let mut depth = 0;
-            let mut proto = self.proto();
-
-            while proto.is_some() {
-                if depth == 255 {
-                    return Err("Encountered an excessively deep prototype chain.".into());
-                }
-
-                if proto.unwrap().has_own_property(name) {
-                    return proto.unwrap().get_local(name, avm, context, (*self).into());
-                }
-
-                proto = proto.unwrap().proto();
-                depth += 1;
-            }
-
-            Ok(Value::Undefined.into())
+            search_prototype(self.proto(), name, avm, context, (*self).into())
         }
     }
 
@@ -200,3 +184,28 @@ impl<'gc> Object<'gc> {
         a.as_ptr() == b.as_ptr()
     }
 }
+
+pub fn search_prototype<'gc>(
+    mut proto: Option<Object<'gc>>,
+    name: &str,
+    avm: &mut Avm1<'gc>,
+    context: &mut UpdateContext<'_, 'gc, '_>,
+    this: Object<'gc>,
+) -> Result<ReturnValue<'gc>, Error> {
+    let mut depth = 0;
+
+    while proto.is_some() {
+        if depth == 255 {
+            return Err("Encountered an excessively deep prototype chain.".into());
+        }
+
+        if proto.unwrap().has_own_property(name) {
+            return proto.unwrap().get_local(name, avm, context, this);
+        }
+
+        proto = proto.unwrap().proto();
+        depth += 1;
+    }
+
+    Ok(Value::Undefined.into())
+}

core/src/avm1/stage_object.rs

@@ -3,7 +3,7 @@
 use crate::avm1::function::Executable;
 use crate::avm1::property::Attribute;
 use crate::avm1::return_value::ReturnValue;
-use crate::avm1::{Avm1, Error, Object, ObjectPtr, ScriptObject, TObject, Value};
+use crate::avm1::{Avm1, Error, Object, ObjectPtr, ScriptObject, TDisplayObject, TObject, Value};
 use crate::context::UpdateContext;
 use crate::display_object::DisplayObject;
 use enumset::EnumSet;
@@ -57,6 +57,26 @@ impl fmt::Debug for StageObject<'_> {
 }
 
 impl<'gc> TObject<'gc> for StageObject<'gc> {
+    fn get(
+        &self,
+        name: &str,
+        avm: &mut Avm1<'gc>,
+        context: &mut UpdateContext<'_, 'gc, '_>,
+    ) -> Result<ReturnValue<'gc>, Error> {
+        // Property search order for DisplayObjects:
+        if self.has_own_property(name) {
+            // 1) Actual properties on the underlying object
+            self.get_local(name, avm, context, (*self).into())
+        } else if let Some(child) = self.display_object.get_child_by_name(name) {
+            // 2) Child display objects with the given instance name
+            Ok(child.object().into())
+        } else {
+            // 3) Prototype
+            crate::avm1::object::search_prototype(self.proto(), name, avm, context, (*self).into())
+        }
+        // 4) TODO: __resolve?
+    }
+
     fn get_local(
         &self,
         name: &str,
@@ -66,15 +86,15 @@ impl<'gc> TObject<'gc> for StageObject<'gc> {
     ) -> Result<ReturnValue<'gc>, Error> {
         self.base.get_local(name, avm, context, this)
     }
+
     fn set(
         &self,
         name: &str,
         value: Value<'gc>,
         avm: &mut Avm1<'gc>,
         context: &mut UpdateContext<'_, 'gc, '_>,
-        this: Object<'gc>,
     ) -> Result<(), Error> {
-        self.base.set(name, value, avm, context, this)
+        self.base.set(name, value, avm, context)
     }
 
     fn call(
@@ -127,10 +147,19 @@ impl<'gc> TObject<'gc> for StageObject<'gc> {
     }
 
     fn has_property(&self, name: &str) -> bool {
-        self.base.has_property(name)
+        if self.base.has_property(name) {
+            return true;
+        }
+
+        if self.display_object.get_child_by_name(name).is_some() {
+            return true;
+        }
+
+        false
     }
 
     fn has_own_property(&self, name: &str) -> bool {
+        // Note that `hasOwnProperty` does NOT return true for child display objects.
         self.base.has_own_property(name)
     }
 
@@ -143,11 +172,19 @@ impl<'gc> TObject<'gc> for StageObject<'gc> {
     }
 
     fn get_keys(&self) -> HashSet<String> {
-        self.base.get_keys()
+        // Keys from the underlying object are listed first, followed by
+        // child display objects in order from highest depth to lowest depth.
+        // TODO: It's possible to have multiple instances with the same name,
+        // and that name will be returned multiple times in the key list for a `for..in` loop.
+        let mut keys = self.base.get_keys();
+        for child in self.display_object.children() {
+            keys.insert(child.name().to_string());
+        }
+        keys
     }
 
     fn as_string(&self) -> String {
-        self.base.as_string()
+        self.display_object.path()
     }
 
     fn type_of(&self) -> &'static str {