I bet you ten bucks that you never were able to execute PHP code through Safari. Safari doesn't run the code through the PHP enginge, it will just read it. No execution. You're not remembering correctly.
What you might have done, is opening a PHP document in an editor like HyperEdit, that does take advantage of the PHP engine, and is also capable of rendering html in a preview pane.
That will still work, so try that. You'll find it here:
http://www.tumultco.com/HyperEdit/