Auto merge of #22514 - jdm:source, r=Manishearth

Implement source for postMessage events

Also make similar-origin iframes access their newly loaded document as soon as the new document is created. This should allow tests that check the event.source property to run correctly.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22499 and fix #12715 and fix #22514.
- [x] There are tests for these changes

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---
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1 files changed, 52 insertions, 6 deletions

diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 6114e353d97..9247ca6afba 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -1419,7 +1419,7 @@ impl ScriptThread {
                     ChangeFrameVisibilityStatus(id, ..) => Some(id),
                     NotifyVisibilityChange(id, ..) => Some(id),
                     Navigate(id, ..) => Some(id),
-                    PostMessage(id, ..) => Some(id),
+                    PostMessage { target: id, .. } => Some(id),
                     UpdatePipelineId(_, _, id, _) => Some(id),
                     UpdateHistoryState(id, ..) => Some(id),
                     RemoveHistoryStates(id, ..) => Some(id),
@@ -1592,9 +1592,19 @@ impl ScriptThread {
                 browsing_context_id,
                 visible,
             ),
-            ConstellationControlMsg::PostMessage(pipeline_id, origin, data) => {
-                self.handle_post_message_msg(pipeline_id, origin, data)
-            },
+            ConstellationControlMsg::PostMessage {
+                target: target_pipeline_id,
+                source: source_pipeline_id,
+                source_browsing_context,
+                target_origin: origin,
+                data,
+            } => self.handle_post_message_msg(
+                target_pipeline_id,
+                source_pipeline_id,
+                source_browsing_context,
+                origin,
+                data,
+            ),
             ConstellationControlMsg::UpdatePipelineId(
                 parent_pipeline_id,
                 browsing_context_id,
@@ -2080,12 +2090,33 @@ impl ScriptThread {
     fn handle_post_message_msg(
         &self,
         pipeline_id: PipelineId,
+        source_pipeline_id: PipelineId,
+        source_browsing_context: TopLevelBrowsingContextId,
         origin: Option<ImmutableOrigin>,
         data: Vec<u8>,
     ) {
         match { self.documents.borrow().find_window(pipeline_id) } {
-            None => return warn!("postMessage after pipeline {} closed.", pipeline_id),
-            Some(window) => window.post_message(origin, StructuredCloneData::Vector(data)),
+            None => return warn!("postMessage after target pipeline {} closed.", pipeline_id),
+            Some(window) => {
+                // FIXME: synchronously talks to constellation.
+                // send the required info as part of postmessage instead.
+                let source = match self.remote_window_proxy(
+                    &*window.global(),
+                    source_browsing_context,
+                    source_pipeline_id,
+                    None,
+                ) {
+                    None => {
+                        return warn!(
+                            "postMessage after source pipeline {} closed.",
+                            source_pipeline_id,
+                        );
+                    },
+                    Some(source) => source,
+                };
+                // FIXME(#22512): enqueues a task; unnecessary delay.
+                window.post_message(origin, &*source, StructuredCloneData::Vector(data))
+            },
         }
     }
 
@@ -2820,6 +2851,21 @@ impl ScriptThread {
 
         window.init_document(&document);
 
+        // For any similar-origin iframe, ensure that the contentWindow/contentDocument
+        // APIs resolve to the new window/document as soon as parsing starts.
+        if let Some(frame) = window_proxy
+            .frame_element()
+            .and_then(|e| e.downcast::<HTMLIFrameElement>())
+        {
+            let parent_pipeline = frame.global().pipeline_id();
+            self.handle_update_pipeline_id(
+                parent_pipeline,
+                window_proxy.browsing_context_id(),
+                incomplete.pipeline_id,
+                UpdatePipelineIdReason::Navigation,
+            );
+        }
+
         self.script_sender
             .send((incomplete.pipeline_id, ScriptMsg::ActivateDocument))
             .unwrap();