5 files changed, 37 insertions, 10 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/dom/document.rs b/components/script/dom/document.rs
index 6e4b4b030e8..4dfb484a301 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -2551,8 +2551,12 @@ impl DocumentMethods for Document {
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-defaultview
-    fn DefaultView(&self) -> Root<Window> {
-        Root::from_ref(&*self.window)
+    fn GetDefaultView(&self) -> Option<Root<Window>> {
+        if self.browsing_context.is_none() {
+            None
+        } else {
+            Some(Root::from_ref(&*self.window))
+        }
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-cookie
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 5b7c9ecf4aa..0b639539f5f 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -1315,7 +1315,10 @@ impl Element {
         }
 
         // Step 5
-        let win = doc.DefaultView();
+        let win = match doc.GetDefaultView() {
+            None => return,
+            Some(win) => win,
+        };
 
         // Step 7
         if *self.root_element() == *self {
@@ -1653,7 +1656,10 @@ impl ElementMethods for Element {
         }
 
         // Step 3
-        let win = doc.DefaultView();
+        let win = match doc.GetDefaultView() {
+            None => return 0.0,
+            Some(win) => win,
+        };
 
         // Step 5
         if *self.root_element() == *self {
@@ -1701,7 +1707,10 @@ impl ElementMethods for Element {
         }
 
         // Step 5
-        let win = doc.DefaultView();
+        let win = match doc.GetDefaultView() {
+            None => return,
+            Some(win) => win,
+        };
 
         // Step 7
         if *self.root_element() == *self {
@@ -1739,7 +1748,10 @@ impl ElementMethods for Element {
         }
 
         // Step 3
-        let win = doc.DefaultView();
+        let win = match doc.GetDefaultView() {
+            None => return 0.0,
+            Some(win) => win,
+        };
 
         // Step 5
         if *self.root_element() == *self {
@@ -1787,7 +1799,10 @@ impl ElementMethods for Element {
         }
 
         // Step 5
-        let win = doc.DefaultView();
+        let win = match doc.GetDefaultView() {
+            None => return,
+            Some(win) => win,
+        };
 
         // Step 7
         if *self.root_element() == *self {
diff --git a/components/script/dom/webidls/Document.webidl b/components/script/dom/webidls/Document.webidl
index 0e5c7b661a6..6b365378c92 100644
--- a/components/script/dom/webidls/Document.webidl
+++ b/components/script/dom/webidls/Document.webidl
@@ -118,7 +118,7 @@ partial /*sealed*/ interface Document {
   // void writeln(DOMString... text);
 
   // user interaction
-  readonly attribute Window/*Proxy?*/ defaultView;
+  readonly attribute Window?/*Proxy?*/ defaultView;
   readonly attribute Element? activeElement;
   boolean hasFocus();
   // attribute DOMString designMode;
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 => (),