Followup 205fa98a, 8dd3460a: move away from isResolved()/isRejected()

jQuery, in its infinite wisdom, deprecated these functions and removed
them in 1.9. This broke VE standalone, and the only reason VE-MW worked
is because of jQuery.migrate.

Change-Id: I3ad920186dc5e794cd165fdaefc76b60ad1acf0a