Fixed OS X 10.6.8 build issue (bug#21862).
* src/nsterm.h (EmacsView): Add missing declarations.
* src/nsterm.m ([EmacsView windowDidBecomeKey]): New method, like
the standard method but without the notification parameter.
Intended to be used for direct calls.
([EmacsView windowDidEnterFullScreen]): Call the non-notification
version of `windowDidBecomeKey'. Made the notification method call
the non-notification method instead of the vice versa.
(NSWindowDidEnterFullScreenNotification): Deleted, no longer
needed.