Fix typo added in r176555: change scm_at_path to scm_for_path.

TBR=eseidel@chromium.org
BUG=786555

Review URL: https://codereview.chromium.org/342993004

git-svn-id: svn://svn.chromium.org/blink/trunk@176560 bbb929c8-8fbe-4397-9dbb-9b2b20218538