R1:4a3d50bcb56d

Improve overflow behavior of Timeline view

Summary:
For text like "MMM", make the right parts of the element scroll.

Also fixed a couple of 1px issues here and there.

Test Plan: Added, viewed UIExamples.

Reviewers: chad, btrahan

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D4152