Even if it supported such things, why not save your money and debug like they used to?
There is nothing stopping you from adding delays in the part you are debugging, and printing to serial where it is step-by-step at a pace you can follow.
You could even write a function that will wait untill you send a character over serial, giving the 'next step' method that so many modern IDE's offer for debugging purposes.
PS: if it is time critical code, trial&error is the only way to go (as far as I know).