lib: don't penalize setInterval() common case

The common case is where setInterval() is called with two arguments,
the callback and the timeout.  Specifying optional arguments in
the parameter list forces common case calls to go through an arguments
adaptor stack frame.

PR-URL: https://github.com/iojs/io.js/pull/1221


Reviewed-By: Trevor Norris <trev.norris@gmail.com>