sample code not working in dart editor -

1. i download dart
2. i start editor , choose 'clock' sample
3. i attempt run sample
4. i message "failed load resource: server responded status of 503 (service unavailable)"

i've tried these things:

i've followed these steps @ different times same effect, don't think pub server going down.

i tried running pub install message "pub install failed, [1] resolving dependencies...timed out trying find package "browser" @ https://pub.dartlang.org."

i tried running pub update got similar message "pub update failed, [1] resolving..... etc."

i have checked internet connection working.

my guess proxy-related. issue 5454 marked "fixed", there's still discussion going on after marked fixed, i'm not sure status today.