- inline this.#render logic.  The initial setTimeout is only used during load(), so run it there instead.
 - .unref() the progress bar's recurring timeout object
 - reuse the progress bar's timeout object with .refresh() instead of making a new one every frame
 - consolidate comments into one line and remove stale comments
 - skip clearing the line on the first frame when resuming the spinner
 - removed the test from $8631 as it was only testing that the very first frame of the spinner didn't clear the line, not any subsequent frames

This is built off of #8631, moving the "skip clearing the line..." logic into a flag that's passed during .resume()