timer: Improve performance of callbacks

setImmediate, setTimeout, and setInterval were called in an inefficient
way, especially in the presence of arguments.  This optimization
improves their performance, with special cases for up to 4 arguments.
Performance of setImmediate increases with 35%, setInterval with 60%,
setTimeout with 70%.

PR-URL: https://github.com/iojs/io.js/pull/406


Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Reviewed-by: Christian Tellnes <christian@tellnes.com>