Auto merge of #22999 - jdm:iframe-replace, r=asajeffrey,cbrewster

Fix replacement logic when navigating nested browsing contexts

These changes also fix a bug where traversing the session history in a nested browsing context did not update the iframe's contentWindow appropriately.

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22996
- [x] There are tests for these changes

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components/script/dom/htmliframeelement.rs

@@ -278,9 +278,7 @@ impl HTMLIFrameElement {
         // see https://html.spec.whatwg.org/multipage/#the-iframe-element:about:blank-3
         let is_about_blank =
             pipeline_id.is_some() && pipeline_id == self.about_blank_pipeline_id.get();
-        // Replacement enabled also takes into account whether the document is "completely loaded",
-        // see https://html.spec.whatwg.org/multipage/#the-iframe-element:completely-loaded
-        let replace = is_about_blank || !document.is_completely_loaded();
+        let replace = is_about_blank;
         self.navigate_or_reload_child_browsing_context(
             Some(load_data),
             NavigationType::Regular,

components/script/script_thread.rs

@@ -1429,7 +1429,7 @@ impl ScriptThread {
                     NotifyVisibilityChange(id, ..) => Some(id),
                     Navigate(id, ..) => Some(id),
                     PostMessage { target: id, .. } => Some(id),
-                    UpdatePipelineId(_, _, id, _) => Some(id),
+                    UpdatePipelineId(_, _, _, id, _) => Some(id),
                     UpdateHistoryState(id, ..) => Some(id),
                     RemoveHistoryStates(id, ..) => Some(id),
                     FocusIFrame(id, ..) => Some(id),
@@ -1617,11 +1617,13 @@ impl ScriptThread {
             ConstellationControlMsg::UpdatePipelineId(
                 parent_pipeline_id,
                 browsing_context_id,
+                top_level_browsing_context_id,
                 new_pipeline_id,
                 reason,
             ) => self.handle_update_pipeline_id(
                 parent_pipeline_id,
                 browsing_context_id,
+                top_level_browsing_context_id,
                 new_pipeline_id,
                 reason,
             ),
@@ -2153,6 +2155,7 @@ impl ScriptThread {
         &self,
         parent_pipeline_id: PipelineId,
         browsing_context_id: BrowsingContextId,
+        top_level_browsing_context_id: TopLevelBrowsingContextId,
         new_pipeline_id: PipelineId,
         reason: UpdatePipelineIdReason,
     ) {
@@ -2163,6 +2166,21 @@ impl ScriptThread {
         if let Some(frame_element) = frame_element {
             frame_element.update_pipeline_id(new_pipeline_id, reason);
         }
+
+        if let Some(window) = self.documents.borrow().find_window(new_pipeline_id) {
+            // Ensure that the state of any local window proxies accurately reflects
+            // the new pipeline.
+            let _ = self.local_window_proxy(
+                &*window,
+                browsing_context_id,
+                top_level_browsing_context_id,
+                Some(parent_pipeline_id),
+                // Any local window proxy has already been created, so there
+                // is no need to pass along existing opener information that
+                // will be discarded.
+                None,
+            );
+        }
     }
 
     fn handle_update_history_state_msg(
@@ -2870,6 +2888,7 @@ impl ScriptThread {
             self.handle_update_pipeline_id(
                 parent_pipeline,
                 window_proxy.browsing_context_id(),
+                window_proxy.top_level_browsing_context_id(),
                 incomplete.pipeline_id,
                 UpdatePipelineIdReason::Navigation,
             );