diff --git a/components/script/dom/bindings/js.rs b/components/script/dom/bindings/js.rs
index ac8da0f8ba6..e3d7247da5a 100644
--- a/components/script/dom/bindings/js.rs
+++ b/components/script/dom/bindings/js.rs
@@ -42,7 +42,6 @@
 //! - `OptionalRootable` and `OptionalRootedRootable`: make rooting `Option` values easy via a `root` method
 //! - `ResultRootable`: make rooting successful `Result` values easy
 //! - `TemporaryPushable`: allows mutating vectors of `JS<T>` with new elements of `JSRef`/`Temporary`
-//! - `OptionalSettable`: allows assigning `Option` values of `JSRef`/`Temporary` to fields of `Option<JS<T>>`
 //! - `RootedReference`: makes obtaining an `Option<JSRef<T>>` from an `Option<Root<T>>` easy
 
 use dom::bindings::trace::JSTraceable;
@@ -367,18 +366,6 @@ impl<T: Reflectable> Assignable<T> for Temporary<T> {
     }
 }
 
-/// Assign an optional rootable value (either of `JS<T>` or `Temporary<T>`) to an optional
-/// field of a DOM type (ie. `Option<JS<T>>`)
-pub trait OptionalSettable<T> {
-    fn assign(&self, val: Option<T>);
-}
-
-impl<T: Assignable<U>, U: Reflectable> OptionalSettable<T> for Cell<Option<JS<U>>> {
-    fn assign(&self, val: Option<T>) {
-        self.set(val.map(|val| unsafe { val.get_js() }));
-    }
-}
-
 
 /// Root a rootable `Option` type (used for `Option<Temporary<T>>`)
 pub trait OptionalRootable<T> {
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 22334b3b2a1..f01dc20a7e1 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -23,7 +23,7 @@ use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::error::Error::{NotSupported, InvalidCharacter};
 use dom::bindings::error::Error::{HierarchyRequest, NamespaceError};
 use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{MutNullableJS, JS, JSRef, Temporary, OptionalSettable, TemporaryPushable};
+use dom::bindings::js::{MutNullableJS, JS, JSRef, Temporary, TemporaryPushable};
 use dom::bindings::js::{OptionalRootable, RootedReference};
 use dom::bindings::utils::reflect_dom_object;
 use dom::bindings::utils::xml_name_type;
diff --git a/components/script/dom/mouseevent.rs b/components/script/dom/mouseevent.rs
index 76c785ee4eb..11a45bbc208 100644
--- a/components/script/dom/mouseevent.rs
+++ b/components/script/dom/mouseevent.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::UIEventBinding::UIEventMethods;
 use dom::bindings::codegen::InheritTypes::{EventCast, UIEventCast, MouseEventDerived};
 use dom::bindings::error::Fallible;
 use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{MutNullableJS, JSRef, RootedReference, Temporary, OptionalSettable};
+use dom::bindings::js::{MutNullableJS, JSRef, RootedReference, Temporary};
 use dom::bindings::utils::reflect_dom_object;
 use dom::event::{Event, EventTypeId};
 use dom::eventtarget::EventTarget;
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index fb336efd85b..83c14208cbb 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -24,7 +24,7 @@ use dom::bindings::error::Fallible;
 use dom::bindings::error::Error::{NotFound, HierarchyRequest, Syntax};
 use dom::bindings::global::GlobalRef;
 use dom::bindings::js::{JS, JSRef, RootedReference, Temporary, Root};
-use dom::bindings::js::{OptionalSettable, TemporaryPushable, OptionalRootedRootable};
+use dom::bindings::js::{TemporaryPushable, OptionalRootedRootable};
 use dom::bindings::js::{ResultRootable, OptionalRootable, MutNullableJS};
 use dom::bindings::trace::JSTraceable;
 use dom::bindings::utils::{Reflectable, reflect_dom_object};
diff --git a/components/script/dom/uievent.rs b/components/script/dom/uievent.rs
index dc6dbb8c756..33c539dd150 100644
--- a/components/script/dom/uievent.rs
+++ b/components/script/dom/uievent.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::UIEventBinding::UIEventMethods;
 use dom::bindings::codegen::InheritTypes::{EventCast, UIEventDerived};
 use dom::bindings::error::Fallible;
 use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{MutNullableJS, JSRef, RootedReference, Temporary, OptionalSettable};
+use dom::bindings::js::{MutNullableJS, JSRef, RootedReference, Temporary};
 
 use dom::bindings::utils::reflect_dom_object;
 use dom::event::{Event, EventTypeId};