benchmark: rename url.parse() benchmark

Rename the url.parse() benchmark from url.js to url-parse.js.
A follow-up commit is going to add another one for url.resolve().

PR-URL: https://github.com/iojs/io.js/pull/184
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>
lib: micro-optimize url.resolve()

Replace the call to Array#splice() with a faster open-coded version
that creates less garbage.

Add a new benchmark to prove it.  With the change applied, it scores
about 5% higher and that is nothing to sneeze at.

PR-URL: https://github.com/iojs/io.js/pull/184
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>