Fix analysis server integration tests on Windows.

Fix analysis server integration tests on Windows.

Platform.script is a URI.  To safely convert it to a Windows path we
need to use .toFilePath(windows: ...).  Previously we used .path,
which resulted in passing nonsensical paths to the VM when invoking
the analysis server subprocess.

BUG=dartbug.com/20252
R=ricow@google.com

Committed: https://code.google.com/p/dart/source/detail?r=38730

[Paul Berry, 2014-07-29 23:03:59]

Rico--

I'm fairly confident this is correct, but since I don't yet have a full Windows
dev environment, I haven't been able to test for certain.  Would you mind
double-checking that this fixes 20252?

Thanks,

Paul

[ricow1, 2014-07-30 09:12:38]

LGTM

I patched it in on my windows box, it works :-)

[Paul Berry, 2014-07-30 12:40:40]

Committed patchset #1 manually as r38730 (presubmit successful).