diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index ee8e93e03ac..9a38807e510 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -503,13 +503,6 @@ unsafe impl<A, B> JSTraceable for fn(A) -> B {
     }
 }
 
-unsafe impl<'a, A, B> JSTraceable for fn(&A) -> B {
-    #[inline]
-    unsafe fn trace(&self, _: *mut JSTracer) {
-        // Do nothing
-    }
-}
-
 unsafe impl<T> JSTraceable for IpcSender<T>
 where
     T: for<'de> Deserialize<'de> + Serialize,
diff --git a/rust-toolchain b/rust-toolchain
index 6f098ceaa7a..b3ce0a23f6e 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly-2018-12-28
+nightly-2019-01-04