Rename Root<T> to DomRoot<T>

In a later PR, DomRoot<T> will become a type alias of Root<Dom<T>>,
where Root<T> will be able to handle all the things that need to be
rooted that have a stable traceable address that doesn't move for the
whole lifetime of the root. Stay tuned.

components/script/dom/extendablemessageevent.rs

@@ -7,7 +7,7 @@ use dom::bindings::codegen::Bindings::ExtendableMessageEventBinding::ExtendableM
 use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::reflect_dom_object;
-use dom::bindings::root::Root;
+use dom::bindings::root::DomRoot;
 use dom::bindings::str::DOMString;
 use dom::bindings::trace::RootedTraceableBox;
 use dom::event::Event;
@@ -32,7 +32,7 @@ impl ExtendableMessageEvent {
     pub fn new(global: &GlobalScope, type_: Atom,
                bubbles: bool, cancelable: bool,
                data: HandleValue, origin: DOMString, lastEventId: DOMString)
-               -> Root<ExtendableMessageEvent> {
+               -> DomRoot<ExtendableMessageEvent> {
         let ev = box ExtendableMessageEvent {
             event: ExtendableEvent::new_inherited(),
             data: Heap::default(),
@@ -52,7 +52,7 @@ impl ExtendableMessageEvent {
     pub fn Constructor(worker: &ServiceWorkerGlobalScope,
                        type_: DOMString,
                        init: RootedTraceableBox<ExtendableMessageEventBinding::ExtendableMessageEventInit>)
-                       -> Fallible<Root<ExtendableMessageEvent>> {
+                       -> Fallible<DomRoot<ExtendableMessageEvent>> {
         let global = worker.upcast::<GlobalScope>();
         let ev = ExtendableMessageEvent::new(global,
                                              Atom::from(type_),