Make nested browsing context navigations check the loaded status of the active document of the nested browsing context.

components/constellation/constellation.rs

@@ -922,6 +922,14 @@ where
     }
 
     fn add_pending_change(&mut self, change: SessionHistoryChange) {
+        debug!(
+            "adding pending session history change with {}",
+            if change.replace.is_some() {
+                "replacement"
+            } else {
+                "no replacement"
+            },
+        );
         self.handle_load_start_msg(
             change.top_level_browsing_context_id,
             change.browsing_context_id,
@@ -1915,13 +1923,29 @@ where
             top_level_browsing_context_id,
             new_pipeline_id,
             is_private,
-            replace,
+            mut replace,
         } = load_info.info;
 
         // If no url is specified, reload.
         let old_pipeline = load_info
             .old_pipeline_id
             .and_then(|id| self.pipelines.get(&id));
+
+        // Replacement enabled also takes into account whether the document is "completely loaded",
+        // see https://html.spec.whatwg.org/multipage/#the-iframe-element:completely-loaded
+        debug!("checking old pipeline? {:?}", load_info.old_pipeline_id);
+        if let Some(old_pipeline) = old_pipeline {
+            replace |= !old_pipeline.completely_loaded;
+            debug!(
+                "old pipeline is {}completely loaded",
+                if old_pipeline.completely_loaded {
+                    ""
+                } else {
+                    "not "
+                }
+            );
+        }
+
         let load_data = load_info.load_data.unwrap_or_else(|| {
             let url = match old_pipeline {
                 Some(old_pipeline) => old_pipeline.url.clone(),
@@ -1964,6 +1988,7 @@ where
                 );
             },
         };
+
         let replace = if replace {
             Some(NeedsToReload::No(browsing_context.pipeline_id))
         } else {
@@ -2214,7 +2239,12 @@ where
         load_data: LoadData,
         replace: bool,
     ) -> Option<PipelineId> {
-        debug!("Loading {} in pipeline {}.", load_data.url, source_id);
+        debug!(
+            "Loading {} in pipeline {}, {}replacing.",
+            load_data.url,
+            source_id,
+            if replace { "" } else { "not " }
+        );
         // If this load targets an iframe, its framing element may exist
         // in a separate script thread than the framed document that initiated
         // the new load. The framing element must be notified about the
@@ -2376,6 +2406,11 @@ where
             self.webdriver.load_channel = None;
         }
 
+        if let Some(pipeline) = self.pipelines.get_mut(&pipeline_id) {
+            debug!("marking pipeline {:?} as loaded", pipeline_id);
+            pipeline.completely_loaded = true;
+        }
+
         // Notify the embedder that the TopLevelBrowsingContext current document
         // has finished loading.
         // We need to make sure the pipeline that has finished loading is the current

components/constellation/pipeline.rs

@@ -89,6 +89,9 @@ pub struct Pipeline {
 
     /// The history states owned by this pipeline.
     pub history_states: HashSet<HistoryStateId>,
+
+    /// Has this pipeline received a notification that it is completely loaded?
+    pub completely_loaded: bool,
 }
 
 /// Initial setup data needed to construct a pipeline.
@@ -355,6 +358,7 @@ impl Pipeline {
             load_data: load_data,
             history_state_id: None,
             history_states: HashSet::new(),
+            completely_loaded: false,
         };
 
         pipeline.notify_visibility(is_visible);

components/constellation/session_history.rs

@@ -37,6 +37,7 @@ impl JointSessionHistory {
     }
 
     pub fn push_diff(&mut self, diff: SessionHistoryDiff) -> Vec<SessionHistoryDiff> {
+        debug!("pushing a past entry; removing future");
         self.past.push(diff);
         mem::replace(&mut self.future, vec![])
     }
@@ -85,6 +86,7 @@ impl JointSessionHistory {
     }
 
     pub fn remove_entries_for_browsing_context(&mut self, context_id: BrowsingContextId) {
+        debug!("removing entries for context {}", context_id);
         self.past.retain(|diff| match diff {
             SessionHistoryDiff::BrowsingContextDiff {
                 browsing_context_id,

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,