Fix recording in live-editor.

Summary: Fix a number of issues around recording that were messed up in previous re-writes.

Test Plan: Create a new recording, verify that all your actions were saved correctly (e.g. drawing, typing, selection).

Reviewers: brian, pamela

Reviewed By: pamela

Subscribers: alexrodrigues, #cs

Differential Revision: http://phabricator.khanacademy.org/D13879