A few live editor tweaks

Summary:
- Adjusts gutter tooltip CSS

Test Plan: - Run tests

Reviewers: john

Subscribers: #cs

Differential Revision: http://phabricator.khanacademy.org/D13167

Conflicts:
	build/js/live-editor.output_pjs.js
	build/workers/pjs/output-tester.js
	build/workers/pjs/test-worker.js
	js/workers/pjs/output-tester.js
	js/workers/pjs/test-worker.js