[chromium] webkitpy-test: executive.py stringify_args error on the release test bot
https://bugs.webkit.org/show_bug.cgi?id=105380

Reviewed by Eric Seidel.

Fix a regression introduced in r137692 where we were double-encoding
the arguments to popen(); this was only an issue on windows, where
we would try to encode something to mbcs, then try to encode it
to unicode as if the input as ascii.

* Scripts/webkitpy/common/system/executive.py:
(Executive.run_command):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139579 268f45cc-cd09-0410-ab3c-d52691b4dbfc