assert: restore TypeError if no arguments

In Node 7.x, calling `throw new assert.AssertionError()` resulted in a
TypeError.

In current master, the same call does not result in an error but, due to
the default option, it results in uninformative output ("undefined
undefined undefined").

This change removes the default argument, restoring a TypeError if there
is no argument. This also will restore our test coverage to 100%. (The
default argument is not tested in our current test suite.)

PR-URL: https://github.com/nodejs/node/pull/12843


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>