auto merge of #2649 : ebalint/servo/2580_JS_T_unrooted_replace, r=jdm

removed .clone() calls
modified from_rooted method parameter: T to &T

src/components/script/dom/validitystate.rs

@@ -19,7 +19,7 @@ impl ValidityState {
     pub fn new_inherited(window: &JSRef<Window>) -> ValidityState {
         ValidityState {
             reflector_: Reflector::new(),
-            window: Cell::new(window.unrooted()),
+            window: Cell::new(JS::from_rooted(window)),
             state: 0,
         }
     }