Fix page loading double-panic if a request fails.

components/script/dom/bindings/js.rs

@@ -91,6 +91,12 @@ impl<T: Reflectable> Unrooted<T> {
         }
     }
 
+    /// Create a new unrooted value from a `Temporary<T>`.
+    #[allow(unrooted_must_root)]
+    pub fn from_temporary(ptr: Temporary<T>) -> Unrooted<T> {
+        Unrooted::from_js(ptr.inner)
+    }
+
     /// Get the `Reflector` for this pointer.
     pub fn reflector<'a>(&'a self) -> &'a Reflector {
         unsafe {

components/script/dom/window.rs

@@ -138,6 +138,14 @@ pub struct Window {
 }
 
 impl Window {
+    #[allow(unsafe_blocks)]
+    pub fn clear_js_context_for_script_deallocation(&self) {
+        unsafe {
+            *self.js_context.borrow_for_script_deallocation() = None;
+            *self.browser_context.borrow_for_script_deallocation() = None;
+        }
+    }
+
     pub fn get_cx(&self) -> *mut JSContext {
         self.js_context.borrow().as_ref().unwrap().ptr
     }
@@ -398,7 +406,6 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
 
 pub trait WindowHelpers {
     fn clear_js_context(self);
-    fn clear_js_context_for_script_deallocation(self);
     fn init_browser_context(self, doc: JSRef<Document>, frame_element: Option<JSRef<Element>>);
     fn load_url(self, href: DOMString);
     fn handle_fire_timer(self, timer_id: TimerId);
@@ -472,14 +479,6 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
         *self.browser_context.borrow_mut() = None;
     }
 
-    #[allow(unsafe_blocks)]
-    fn clear_js_context_for_script_deallocation(self) {
-        unsafe {
-            *self.js_context.borrow_for_script_deallocation() = None;
-            *self.browser_context.borrow_for_script_deallocation() = None;
-        }
-    }
-
     /// Reflows the page if it's possible to do so and the page is dirty. This method will wait
     /// for the layout thread to complete (but see the `TODO` below). If there is no window size
     /// yet, the page is presumed invisible and no reflow is performed.

components/script/script_task.rs

@@ -25,7 +25,7 @@ use dom::bindings::codegen::InheritTypes::{ElementCast, EventTargetCast, HTMLIFr
 use dom::bindings::conversions::FromJSValConvertible;
 use dom::bindings::conversions::StringificationBehavior;
 use dom::bindings::js::{JS, JSRef, Temporary, OptionalRootable, RootedReference};
-use dom::bindings::js::{RootCollection, RootCollectionPtr};
+use dom::bindings::js::{RootCollection, RootCollectionPtr, Unrooted};
 use dom::bindings::refcounted::{LiveDOMReferences, Trusted, TrustedReference};
 use dom::bindings::structuredclone::StructuredCloneData;
 use dom::bindings::trace::JSTraceable;
@@ -312,14 +312,15 @@ impl<'a> ScriptMemoryFailsafe<'a> {
 
 #[unsafe_destructor]
 impl<'a> Drop for ScriptMemoryFailsafe<'a> {
+    #[allow(unrooted_must_root)]
     fn drop(&mut self) {
         match self.owner {
             Some(owner) => {
                 unsafe {
                     let page = owner.page.borrow_for_script_deallocation();
                     for page in page.iter() {
-                        let window = page.window().root();
-                        window.r().clear_js_context_for_script_deallocation();
+                        let window = Unrooted::from_temporary(page.window());
+                        (*window.unsafe_get()).clear_js_context_for_script_deallocation();
                     }
                     *owner.js_context.borrow_for_script_deallocation() = None;
                 }