Auto merge of #27163 - alarsyo:23053-layout-queries-disconnected-frames-panic, r=jdm

Return Option for Window's layout channel

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`Window::layout_chan()` now returns an `Option<Sender<Msg>>`, returning `None` if the window is dead.

FIX #26969
FIX #26429
FIX #21208
FIX #19092
FIX #22559
FIX #22584
FIX #22652

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #23053

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- [x] There are tests for these changes

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This is my first contribution, I'm trying to figure things out!

This fix passes the test case shown in #23053, however I don't know what the behavior should be in `Document` and `ScriptThread` if `Window::is_alive()` is false : simply ignore it, don't do anything ? Or is this something that should not happen now that we return false in `Window::force_reflow()` ?

I'm not sure about the directory where the test case should go, any advice?

components/script/dom/document.rs

@@ -804,10 +804,10 @@ impl Document {
         self.quirks_mode.set(mode);
 
         if mode == QuirksMode::Quirks {
-            self.window
-                .layout_chan()
-                .send(Msg::SetQuirksMode(mode))
-                .unwrap();
+            match self.window.layout_chan() {
+                Some(chan) => chan.send(Msg::SetQuirksMode(mode)).unwrap(),
+                None => warn!("Layout channel unavailable"),
+            }
         }
     }
 
@@ -3724,13 +3724,15 @@ impl Document {
             })
             .cloned();
 
-        self.window
-            .layout_chan()
-            .send(Msg::AddStylesheet(
-                sheet.clone(),
-                insertion_point.as_ref().map(|s| s.sheet.clone()),
-            ))
-            .unwrap();
+        match self.window.layout_chan() {
+            Some(chan) => chan
+                .send(Msg::AddStylesheet(
+                    sheet.clone(),
+                    insertion_point.as_ref().map(|s| s.sheet.clone()),
+                ))
+                .unwrap(),
+            None => return warn!("Layout channel unavailable"),
+        }
 
         DocumentOrShadowRoot::add_stylesheet(
             owner,
@@ -3744,10 +3746,10 @@ impl Document {
     /// Remove a stylesheet owned by `owner` from the list of document sheets.
     #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
     pub fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
-        self.window
-            .layout_chan()
-            .send(Msg::RemoveStylesheet(s.clone()))
-            .unwrap();
+        match self.window.layout_chan() {
+            Some(chan) => chan.send(Msg::RemoveStylesheet(s.clone())).unwrap(),
+            None => return warn!("Layout channel unavailable"),
+        }
 
         DocumentOrShadowRoot::remove_stylesheet(
             owner,