servo: Merge #8558 - Dispatch load events for cross origin iframes. Resolves #6672 (from jdm:crossoriginiframeload); r=glennw

Splitting it out from #6677.

Source-Repo: https://github.com/servo/servo
Source-Revision: 51c19fd733a863f2fae05e693795dbecce69f2ed

servo/components/script/script_task.rs

@@ -1006,6 +1006,9 @@ impl ScriptTask {
                 self.handle_tick_all_animations(pipeline_id),
             ConstellationControlMsg::WebFontLoaded(pipeline_id) =>
                 self.handle_web_font_loaded(pipeline_id),
+            ConstellationControlMsg::DispatchFrameLoadEvent {
+                target: pipeline_id, parent: containing_id } =>
+                self.handle_frame_load_event(containing_id, pipeline_id),
             ConstellationControlMsg::GetCurrentState(sender, pipeline_id) => {
                 let state = self.handle_get_current_state(pipeline_id);
                 sender.send(state).unwrap();
@@ -1535,6 +1538,15 @@ impl ScriptTask {
         }
     }
 
+    /// Notify the containing document of a child frame that has completed loading.
+    fn handle_frame_load_event(&self, containing_pipeline: PipelineId, id: PipelineId) {
+        let page = get_page(&self.root_page(), containing_pipeline);
+        let document = page.document();
+        if let Some(iframe) = document.find_iframe_by_pipeline(id) {
+            iframe.iframe_load_event_steps();
+        }
+    }
+
     /// The entry point to document loading. Defines bindings, sets up the window and document
     /// objects, parses HTML and CSS, and kicks off initial layout.
     fn load(&self, metadata: Metadata, incomplete: InProgressLoad) -> Root<ServoHTMLParser> {