[GSOC 2016] persisting tabs across app restart

Hi, I'm working on persisting tabs across app restart, for the event in 
a tab project.

The basic mechanism in the tabmail interface is to save a JS object that 
contains the tab data/state as a JS object with the persistTab function 
and then in the restoretab function use that data/state in a call to 
openTab.

So what we want to store is the same as the aArgs argument to openTab, 
which we kept when opening the tab (as window.arguments[0] from within 
the iframe).  Seems simple enough, but...

In that aArgs object the calendarEvent, calendar, and 
initialStartDateValue values are "XPCWrappedNative_NoHelper"[1]  but 
between when aArgs is saved by persistTab and passed to restoreTab these 
values have become standard empty JS objects.

(In persistTab I have tried just returning 
aTab.iframe.contentWindow.arguments[0] and using Object.assign() to 
clone that object to a new one and returning it.  Same result for both.)

Any ideas on how to solve this?

Thanks,
-Paul

[1] 
https://dxr.mozilla.org/comm-central/source/mozilla/js/xpconnect/src/XPCWrappedNativeJSOps.cpp#644