DevTools FE uploader: fix sending mail to multiple recipients Previously, the FE uploader wasn't properly sending notification emails to multiple recipients because the to_address must be a list otherwise it will be treated as a list with 1 email address. [1] [1] https://docs.python.org/2/library/smtplib.html BUG=none [email protected] Review URL: https://codereview.chromium.org/2351133003 .