1 files changed, 10 insertions, 1 deletions
diff --git a/src/components/script/dom/bindings/js.rs b/src/components/script/dom/bindings/js.rs
index b5a83b01e7c..bbceae0ad6d 100644
--- a/src/components/script/dom/bindings/js.rs
+++ b/src/components/script/dom/bindings/js.rs
@@ -47,7 +47,7 @@ use layout_interface::TrustedNodeAddress;
 use script_task::StackRoots;
 
 use std::cast;
-use std::cell::RefCell;
+use std::cell::{Cell, RefCell};
 use std::kinds::marker::ContravariantLifetime;
 
 /// A type that represents a JS-owned value that is rooted for the lifetime of this value.
@@ -269,6 +269,15 @@ impl<T: Assignable<U>, U: Reflectable> OptionalSettable<T> for Option<JS<U>> {
     }
 }
 
+impl<T: Assignable<U>, U: Reflectable> OptionalSettable<T> for Cell<Option<JS<U>>> {
+    fn assign(&mut self, val: Option<T>) {
+        let mut item = self.get();
+        item.assign(val);
+        self.set(item);
+    }
+}
+
+
 /// Root a rootable Option type (used for Option<Temporary<T>>)
 pub trait OptionalRootable<T> {
     fn root<'a, 'b>(self) -> Option<Root<'a, 'b, T>>;