time out startup tests sooner (#35)
time out startup tests sooner (#35)

Due to https://github.com/flutter/flutter/issues/5477 flutter run
is unable to exit when an error occurs. Currently our tests get
stuck until the default timeout of 10 minutes expires. That's way
too long for a startup test. This PR customizes the timeout for
startup tests to 2 minutes.
flutter/cocoon,flutter/cocoon,flutter/cocoon,flutter/cocoon,flutter/cocoon,flutter/cocoon,flutter/cocoon,flutter/cocoon,flutter/cocoon