Added an utility function to ensure that we don't "asanize" the same image twice.

BUG=

Review URL: https://codereview.appspot.com/6817076

git-svn-id: http://sawbuck.googlecode.com/svn/trunk/syzygy@1220 15e8cca8-e42c-11de-a347-f34a4f72eb7d
6 files changed