Make stream_periodic4_test more resilient against computer loads.

Make stream_periodic4_test more resilient against computer loads.

BUG= http://dartbug.com/9367

Committed: https://code.google.com/p/dart/source/detail?r=20849

[Lasse Reichstein Nielsen, 2013-04-03 09:50:02]

https://codereview.chromium.org/12578019/diff/2001/tests/lib/async/stream_per...
File tests/lib/async/stream_periodic4_test.dart (right):

https://codereview.chromium.org/12578019/diff/2001/tests/lib/async/stream_per...
tests/lib/async/stream_periodic4_test.dart:19: // Test failed. Could be, because
the machine was under load.
Remove comma.
Why fail? If the fails under load, it is flaky, and should be disabled. If you
give up testing, just exit, but don't fail.

[Lasse Reichstein Nielsen, 2013-04-03 09:50:06]

lgtm

[floitsch, 2013-04-03 11:24:01]

https://codereview.chromium.org/12578019/diff/2001/tests/lib/async/stream_per...
File tests/lib/async/stream_periodic4_test.dart (right):

https://codereview.chromium.org/12578019/diff/2001/tests/lib/async/stream_per...
tests/lib/async/stream_periodic4_test.dart:19: // Test failed. Could be, because
the machine was under load.
On 2013/04/03 09:50:02, Lasse Reichstein Nielsen wrote:
> Remove comma.
> Why fail? If the fails under load, it is flaky, and should be disabled. If you
> give up testing, just exit, but don't fail.

This comment applies just for this iteration. In the beginning the tests have
little time, and over time we give it more and more time. If, at the end, it
still fails then we actually fail. There is no reason it should ever take more
than 2 seconds. Not even under load.

[floitsch, 2013-04-03 12:06:58]

Committed patchset #4 manually as r20849 (presubmit successful).