Stops the Stopwatch.
The elapsedTicks count stops increasing after this call. If the Stopwatch is currently not running, then calling this method has no effect.
Source
/**
* Stops the [Stopwatch].
*
* The [elapsedTicks] count stops increasing after this call. If the
* [Stopwatch] is currently not running, then calling this method has no
* effect.
*/
void stop() {
if (!isRunning) return;
_stop = _now();
}