Currently folks who use git to check out the chromium repo cannot run the layout tests on vista because run_webkit_tests.py checks for the existence of platform/chromium-win-vista and git, unlike SVN, will not create an empty directory if one exists upstream.  This works around the issue by adding a dummy file to platform/chromium-win-vista so the directory always is there.

Review URL: http://codereview.chromium.org/201128

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@26293 0039d316-1c4b-4281-b951-d872f2087c98