Avoid an index-out-of-bounds error in ScriptMemoryFailsafe.

Fixes #11059.
Fixes #11400.
Fixes #11481.
Fixes #11671.
Fixes #11682.

2 files changed, 10 insertions, 2 deletions

diff --git a/components/script/dom/browsingcontext.rs b/components/script/dom/browsingcontext.rs
index 99c72e1e4be..1b78fb7572d 100644
--- a/components/script/dom/browsingcontext.rs
+++ b/components/script/dom/browsingcontext.rs
@@ -108,6 +108,12 @@ impl BrowsingContext {
         Root::from_ref(&self.history.borrow()[self.active_index.get()].document)
     }
 
+    pub fn maybe_active_document(&self) -> Option<Root<Document>> {
+        self.history.borrow().get(self.active_index.get()).map(|entry| {
+            Root::from_ref(&*entry.document)
+        })
+    }
+
     pub fn active_window(&self) -> Root<Window> {
         Root::from_ref(self.active_document().window())
     }
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 63fed6cf115..eec1853239e 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -422,8 +422,10 @@ impl<'a> Drop for ScriptMemoryFailsafe<'a> {
             Some(owner) => {
                 let context = owner.browsing_context.get();
                 for context in context.iter() {
-                    let window = context.active_window();
-                    window.clear_js_runtime_for_script_deallocation();
+                    if let Some(document) = context.maybe_active_document() {
+                        let window = document.window();
+                        window.clear_js_runtime_for_script_deallocation();
+                    }
                 }
             }
             None => (),