From f8c7235f73865705f2f1104619ea3c753fbb3c9b Mon Sep 17 00:00:00 2001
From: Mariot Chauvin <mariot.chauvin@gmail.com>
Date: Fri, 10 Mar 2017 10:27:58 +0000
Subject: [PATCH] Access browsing context without panic

Current browsing context accessor in Document unwrap the browsing context option which prevents document to handle correctly the case when there is no browsing context.
---
 components/script/dom/document.rs | 2 +-
 components/script/dom/window.rs   | 9 +++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 29d7227dee9..14786820ffc 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -390,7 +390,7 @@ impl Document {
     #[inline]
     pub fn browsing_context(&self) -> Option<Root<BrowsingContext>> {
         if self.has_browsing_context {
-            Some(self.window.browsing_context())
+            self.window.maybe_browsing_context()
         } else {
             None
         }
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 64a303c9412..571cf907a71 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -319,10 +319,15 @@ impl Window {
         &self.image_cache_thread
     }
 
+    /// This can panic if it is called after the browsing context has been discarded
     pub fn browsing_context(&self) -> Root<BrowsingContext> {
         self.browsing_context.get().unwrap()
     }
 
+    pub fn maybe_browsing_context(&self) -> Option<Root<BrowsingContext>> {
+        self.browsing_context.get()
+    }
+
     pub fn bluetooth_thread(&self) -> IpcSender<BluetoothRequest> {
         self.bluetooth_thread.clone()
     }
@@ -608,7 +613,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-parent
     fn GetParent(&self) -> Option<Root<BrowsingContext>> {
         // Steps 1. and 2.
-        if self.browsing_context().is_discarded() {
+        if self.maybe_browsing_context().map_or(true, |c| c.is_discarded()) {
             return None;
         }
         match self.parent() {
@@ -622,7 +627,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-top
     fn GetTop(&self) -> Option<Root<BrowsingContext>> {
         // Steps 1. and 2.
-        if self.browsing_context().is_discarded() {
+        if self.maybe_browsing_context().map_or(true, |c| c.is_discarded()) {
             return None;
         }
         // Step 5.