Simplify easy-mmode-define-navigation

* lisp/emacs-lisp/easy-mmode.el (easy-mmode-define-navigation):
Simplify a one-argument call to "or" and use buffer-narrowed-p instead
of checking that condition by hand.
1 job for master in 52 minutes and 43 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #862
test-all

00:52:43

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:309: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:284: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
make: *** [check-expensive] Error 2
Makefile:962: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1