LibWeb: Add some missing events in EventWrapperFactory

I noticed some events we being wrapped into a generic Event while
working on CustomEvent. This also adds PageTransitionEvent's
constructor to the WindowObject.

I'm not sure if this is all of them.

Userland/Libraries/LibWeb/Forward.h

@@ -178,6 +178,8 @@ class ImageData;
 class MessageChannel;
 class MessageEvent;
 class MessagePort;
+class PageTransitionEvent;
+class SubmitEvent;
 class WebSocket;
 }