This is needed if you do not have VS in your PATH on purpose and makes life easy if you do not have it there by accident.

Review URL: http://codereview.chromium.org/112098

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@17854 0039d316-1c4b-4281-b951-d872f2087c98