servo: Merge #9317 - DOMContentLoaded should bubble (from MonsieurLanza:DomContentLoadedBubbles); r=KiChjang

DOMContentLoaded event is currently set as non bubbling event.
Test :
./tests/wpt/web-platform-tests/html/syntax/parsing/the-end.html

Source-Repo: https://github.com/servo/servo
Source-Revision: 0c500a9da53145bf065804794137e2b4fc295dee

servo/components/script/dom/document.rs

@@ -1352,7 +1352,7 @@ impl Document {
 
         let event = Event::new(GlobalRef::Window(self.window()),
                                atom!("DOMContentLoaded"),
-                               EventBubbles::DoesNotBubble,
+                               EventBubbles::Bubbles,
                                EventCancelable::NotCancelable);
         let doctarget = self.upcast::<EventTarget>();
         let _ = doctarget.DispatchEvent(event.r());