Add tie symbol (~)

Summary:
Add real support for the tie symbol. Also, get rid of any of the
leftover bad support

Test Plan:
 - See the new normal tests succeed
 - See huxley tests didn't change except the new ones, which looks good

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D7772