Fixes#117659
It turns out this was due to the output-suppression timer introduced
recently as part of cleaning up the output (#109206); on success, the
script would wait 10 minutes for the timeout to expire. This didn't
affect CI because this feature doesn't apply in CI (as detected by
lack of color on stdout.)
Fix the issue by cleaning up the timer on success in the same way
as on failure.
While here, clean up the final summary messages slightly,
and also cut the trailing space that printProgress was leaving
on each line.
* [Flutter_tools] Ensure service worker starts caching assets since the first launch
* [flutter_tools] add comment to give some context on self.clients.claim()
* [flutter_tools] add comment to give some context on self.clients.claim()
