Auto merge of #11548 - kevgs:default_view2, r=Ms2ger

Make Document::DefaultView return a null value when there's no browsing context

Fixes #11469.

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11548)
<!-- Reviewable:end -->

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

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 {

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;