core: Ensure bitmaps run post_instantiate

core/src/avm1/globals/movie_clip.rs

@@ -221,6 +221,13 @@ fn attach_bitmap<'gc>(
                         display_object.into(),
                         depth,
                     );
+                    display_object.post_instantiation(
+                        &mut activation.context,
+                        display_object.into(),
+                        None,
+                        Instantiator::Avm1,
+                        true,
+                    );
                 }
             }
         }

core/src/display_object/bitmap.rs

@@ -1,10 +1,12 @@
 //! Bitmap display object
 
+use crate::avm1;
 use crate::backend::render::BitmapHandle;
 use crate::context::{RenderContext, UpdateContext};
 use crate::display_object::{DisplayObjectBase, TDisplayObject};
 use crate::prelude::*;
 use crate::types::{Degrees, Percent};
+use crate::vminterface::{AvmType, Instantiator};
 use gc_arena::{Collect, Gc, GcCell};
 
 /// A Bitmap display object is a raw bitamp on the stage.
@@ -97,6 +99,25 @@ impl<'gc> TDisplayObject<'gc> for Bitmap<'gc> {
         }
     }
 
+    fn post_instantiation(
+        &self,
+        context: &mut UpdateContext<'_, 'gc, '_>,
+        _display_object: DisplayObject<'gc>,
+        _init_object: Option<avm1::Object<'gc>>,
+        _instantiated_by: Instantiator,
+        run_frame: bool,
+    ) {
+        if self.avm_type() == AvmType::Avm1 {
+            context
+                .avm1
+                .add_to_exec_list(context.gc_context, (*self).into());
+        }
+
+        if run_frame {
+            self.run_frame(context);
+        }
+    }
+
     fn run_frame(&self, context: &mut UpdateContext<'_, 'gc, '_>) {
         if let Some(bitmap_data) = &self.0.read().bitmap_data {
             let bd = bitmap_data.read();