Fix for PHP 5.4 standard compatibility

Hi Brock Ellis,

First I have to thank you very much for your PHP progress bar code for learning.
But after I cloned your respiratory. I have to fix a little code for my strict PHP environment.
(I'm using XAMPP with PHP 5.4.7)

Maybe you can merge this code to improve them little. Maybe for next person who can clone your code get worked result easily.

Thank you