Summary: Send-on-enter and autocomplete both listen for "return" keypresses, and could race. Have autocomplete let other handlers take a shot at the action before it does. Also, fix a case where ":)" and the suffix list (which lets you type `someone is 100% to blame here (@epriestley)` and get the results you want) interacted badly, so ":)" cancels the autocompleter like ":3" does. Test Plan: - Typed "@xxx" and mashed return real fast over and over again while reloading the page. Before: sometimes handlers raced and text submitted. After: always handled by autocomplete behavior. - Typed ":", ")", "<return>", sent an emoticon (previously: no). Reviewers: chad, amckinley Reviewed By: chad Subscribers: xxx Differential Revision: https://secure.phabricator.com/D17794