The nsIDOMPageTransitionEvent interface is used for the pageshow and
 pagehide events, which are generic events that apply to both page
 load/unload and saving/restoring a document from session history.
[scriptable, uuid(b712418b-376f-4f75-b156-5d9ad99fe51f)]
interface nsIDOMPageTransitionEvent : nsIDOMEvent


 Set to true if the document has been or will be persisted across
 firing of the event.  For example, if a document is being cached in
 session history, |persisted| is true for the PageHide event.
readonly attribute boolean persisted


void initPageTransitionEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean canCancelArg, in boolean persisted)