Add --build-directory option to test.py.

Add --build-directory option to test.py.

Fix problem when no --step-name option is present.

BUG=dart:6885
Committed: https://code.google.com/p/dart/source/detail?r=15280

[Bill Hesse, 2012-11-23 10:38:55]

I think this is better than specifying the build directory explicitly.

[ahe, 2012-11-23 11:36:39]

On 2012/11/23 10:38:55, Bill Hesse wrote:
> I think this is better than specifying the build directory explicitly.

I disagree.

[ahe, 2012-11-23 12:28:34]

Thank you, Bill!

LGTM

[Bill Hesse, 2012-11-23 12:53:38]

https://codereview.chromium.org/11308179/diff/5001/tests/standalone/io/test_r...
File tests/standalone/io/test_runner_exit_code_script.dart (right):

https://codereview.chromium.org/11308179/diff/5001/tests/standalone/io/test_r...
tests/standalone/io/test_runner_exit_code_script.dart:16: new
ProgressIndicator.fromName(progressType, startTime, false);
Added so that the test prints out a "step failed" message with the buildbot
progress indicator.

[kustermann, 2012-11-23 13:14:16]

LGTM